This is something that must be always take in account if you are using local fiat that can get such high inflation versus USD dollar.
Something like this would be a disaster with euro... but this is also a "lesson" for all of us. Our local currency after many years now are literally devalued.
Even people that have invested heavily in real estate now have no liquidity, and their homes are worthing maybe more but compared to other currencies these are just devalued.
Well, in a "open world" thanks to new technology, thinking that economy and currencies are just "local" is a great mistake.

Yes, basically you have all the world competing to make money, and arbitrage is always potentially there.

Heaps of people trying to buy and sell from one place to another to make a quick buck.

All of that keeps the prices of Bitcoin pretty much the same worldwide.

If it wasn't the same in one currency then there's money to be made by arbitrage, and you can believe that there are people doing that all the time, bringing the price difference to almost nothing,

That's the risk of living in a developing country with an unstable currency - because I'm also in a country like that where if I pull from the past years, then my currency against the USD is increasingly powerless. But even so I think that it is not a reason for someone to delay/not invest their money in Bitcoin, because there is no loss for them to put their money in Bitcoin, it is the best asset to fight inflation in the long term. Therefore, for people who want to invest in Bitcoin, the sooner they invest, the better, because their currency will weaken, while in the long term Bitcoin will become stronger.

The solution that I've seen is they're sending someone to a better country to work in there and send them money to spend for which is either pounds or US dollars. In the toughest times, our natural instinct works and solutions are being found per person or per family that has to deal with such hardship. Because it is pointless for the people there to work hard although they have to and the salary they receive is just par with their meal day allowance or even less. That's why working offshore is one solution aside from other hustles that these great people have been doing to survive.

Even you buy the dip and it is a long term investment like 10 to 15 years the person will still at the losing side of the local exchange rate reduce. In bitcoin investment you don't think only the profit but what will happen if the exchange declined below your expectation. Let me give some examples. As It was said in the Op, right now the local exchange rate is $1 to N1,550 amd you should know that bitcoin is calculated with dollar and not with naira so if dollar fall it affects Bitcoin investors because when you sell it will not come out as expected. If I have 0.08 BTC and $1 is N1,550 so if you sell it now it will come out as correct BTC price 1btc to $96,689.40 X the fraction of BTC you have as 0.08 BTC equal to $7,737.68 X N1,550 Naira. And what you will receive as local currency is N11,993,404 (96,689.40 X 0.08 =$7,737.68. then $7,737.68 X N1,550 = N11,993,404).
But in ten years time when the government has been changed and the price of dollar has be devalued to $1 = N500 and you still have the 0.08 BTC amd Bitcoin price is probably $250,586.60, the amount you will get from dollar from the 0.08 BTC is $20,046.928 and if the $/NGN is N500 your final output will be N10,023,464 as your investment outcome for the 10 years. Here I checked it from $/NGN. Bitcoin will rise but local currency with dollar exchange rate will affect you. So always have an alternative thinking in investment. If this happens what should be the next steps. Those are things to think before investing.

Even if the money is in BTC, if dollar fall drastically, the person will still lose unless dollar rise or stable at the price you bought and Bitcoin rise then you make good profit. But we have to calculate the four corners of the investment.

You are not using Bitcoin to buy things in you country and definitely you must convert it or sell it back to your local currency for spending then you will know how much came out from your local currency if the price of $/your local currency is very low. It is not a big assertion here but just understand my view point in the market.

If someone invested at the time when the $/your local currency exchange is high and in 10 years time the exchange rate is very low. Are you losing or gaining? Calculate well.

I am not making any comparison between Bitcoin and fiat but I am trying to say that if the US dollar with a local currency exchange reduced in the future, it will affect the investors. Please you can read the first paragraph of this comment. Your calculation is base on the current price but in the future or 10 to 15 years to come when the local exchange is $1 to N500 or below 1 BTC to Naira will definitely reduce so that is my point.

In conclusion it is only few understand my point but others are only talking about the current price and local currency exchange but my assertion is the future of those countries that the $/local currency change when new government takes over power. Right now the new government in Nigeria devalued the country currency for US dollar but another government will come and might decide to make the local currency strong and for that it will affect those who are investing in bitcoin because we are buying as a higher rate and if the time to sell it is a lower exchange rate then we are at the losing side.

We know that bitcoin is one of the best profitable crypto in cryptocurrency market. So I believe that if we want to invest in bitcoin, I think that it will be very prefer for us. But we know that cryptocurrency market is always depending on up and down.
So when we saw bitcoin price will go down in crypto currency market, then it will be very prefer time for invest in this crypto. Because we know that down market is very prefer time for invest. But we know that bitcoin price is $97k up in this time, so in this time invest in bitcoin will be risky for us.

That is why they must research to get all of the info they need so they know what they can prepare before they start investing in Bitcoin. When they know about what @OP telling, they can anticipate it so they will not have any problem when starting to invest in Bitcoin.

The other important thing is they must use allocation money to invest which is the money that they don't use for anything. That will make them feel comfortable when they start investing. If they can know what is the risk that they can meet in the middle of the Bitcoin investment journey, they will have a way to solve every problem that occurs.

They will not confuse how to get the answer of every problem that they face. They preparation will be in high because they know that the risk can occurs anytime.

In fact, the local currency is decreasing in value, and I can see it from the exchange rate to the Dollar. The same thing happened to the currency in my country, last year I saw that $ 1 = Rp. 15,500, but now $ 1 = Rp. 16,200. That shows that the local currency is decreasing in value, and if I had exchanged it to $ last year, it would have been profitable. However, it should be noted that if I exchange my local money to Bitcoin, the profit in value is much more profitable than keeping it in $. And if I look back at the past around 2016, I saw the Rupiah Rp exchange rate was around 1 $ = Rp. 14,045, while at that year the value of Bitcoin was only around $ 700 or Rp. 10,000,000. From here I think we can all conclude that it is never too late to invest in Bitcoin.

Bitcoin investmentway is another tamzuki hall’s opacity and market volatility can be the price of bitcoin and that can change quickly. Experts say that big financial damage may be caused in the case of modesty. Although Bitcoin is at risk in investing, it’s a lot of chances. Besides, there is no central regulator or owner of the Bitcoin market, there is no increase in risk like cheating and hacking. But why does it not have evidence that you can fully transact in terms of many transactions in this regard. And through this many people are being victims of cheating. So even if bitcoin investments have a little risk, it can make your future stronger at one time.

This is the same in my nation as well. In my nation the ratio of dollar got worse for us as well, but at the same time if you invested into bitcoin, not only your 20k dollar bitcoin investment was 200k local currency, also the 100k bitcoin price meant you nearly had 3 million in local currency as well. Because dollar ratio changed as well, and when the dollar ratio changes that way, it is not always about dollar getting stronger, there is inflation in dollar too so in 2025 dollar worths a lot less than 2010, but my local currency worths even less, it got even weaker.

This is the reason, even when dollar gets weaker, if your fiat gets weaker than that, it means dollar will worth a lot more against it. When I invest into bitcoin, I make profit in double manner.