Do you mean how many Bitcoins to keep them invested generating passive income, or to hold them inside a hardware wallet, using them along the years after retirement, until they finish?

Let's consider the second case. It's hard to estimate an amount, because economy is out of control. Prices of goods and services are skyrocketing, while Bitcoin's price is pretty volatile. Talking about current rates, and what I consider to be a comfortable life for a person alone, each Bitcoin would last for about 36 months, so let's say 3 years.

For how long does a retired person is likely to live? Another 15 or 20 years? Then I would need 6 pieces of Bitcoin.

I’d say it’s tough to figure out exactly how much you’d need. Bitcoin’s price is all over the place, and there’s a lot that could change in the next decade or two. If I had to guess, I’d want enough to cover at least 10–15 years of decent living. So, maybe around 5–6 BTC? That could change if Bitcoin sees a huge surge or crashes. If I were retiring now, though, I’d probably aim for about 2 BTC, assuming Bitcoin hits 100k by then. But honestly, it’s more about making sure you have enough to be comfortable and not rely on anything else.

Of course if I could have 10 BTC but rationally it is impossible to have if you look at the ability of myself then reaching 1 BTC is still possible to have and that is enough for retirement later.

Let's say in the next 20 years bitcoin can be more than $500K then it is more than enough for my country without any state assistance or insurance because the amount of money is very large.

If you choose 10 BTC then that's too much, so like I said - be realistic about this decision.

Who can reach 100 BTC if they buy from now on? Except conglomerates.

We won't know how much BTC is worth in the next 10 - 30 years maybe the price will be even higher... if we start from now to collect retirement then it will be quite difficult to 1 BTC if only relying on a fixed salary when still working... So my dream is to have more BTC, even 5 BTC is what I want... but I don't know if this will be achieved or not, I will just keep trying to collect it.

For me, I also did love to have as from 10 up btc for retirement, and it doesn't matter what the price of bitcoin turn out to be in the future, but as long as the price remain above $100,000, I am very good.

At a hundred thousand dollar, 10 or more bitcoin will be worth a million dollars or more, this is enough for me to have a good retirement with my wife, set up companies and have trusted people run it for me, money made from this companies can be invested back in bitcoin to further increase my bitcoin stash and as well as add to my retirement funds, life is actually good when there is money  😊

100 BTC is what having though I know that it's very hard to achieve such volume of Bitcoin but based on the survey I have to choose that of 100 Bitcoin as I know there are lot of things to be achieved in life, and also considering my age 100 Bitcoin is fair enough to have before I get my 90-100 years time and having 100 Bitcoin can real sustain me depending on the price of Bitcoin in the future.

I think 1 Bitcoin is already a huge capital. We must not forget that people constantly lose access to their private keys. There can be different reasons - a technical error, force majeure, bad memory, imprisonment, death, and so on.

Each lost Bitcoin forever increases the value of those coins that remain in circulation. The price of Bitcoin will grow over time.

Even in the current bull period, I expect the price to be $ 200,000. This is quite enough to live comfortably for many years.

Of course, I would like to have more coins. After all, a bull period always follows a bear period. However, in my opinion, even one Bitcoin is a great result. I would like to own 1 Bitcoin! And 2 Bitcoins - even better!

10 BTC is quite a huge amount in my country and most people even leave their entire life without securing an amount worth 1 BTC not to talk of 10 BTC. For me, 10 BTC is unrealistic for me considering how much i DCA every month. Though am still young of which it will take me like 30 years to reach my retirement age and i don't know if i will still have a stable job to keep DCAing in the future but let me not be greedy. I can own up to 5 BTC before my retirement age, it can still be more than that but since i will also be using part of my money to invest on real life assets, i may or may not exceed my target of 5 BTC before my retirement. And this will be on the ground of consistent DCA, but if peradventure due to unforeseen circumstances in the future that may cause me to pause my DCAing at some point, i might not own up to that 5 BTC.

No I realized after writing that's not possible, it was only a dream, but dreaming is still allowed 

Better to check first what is your plan after you accumulate that volume since even how huge the money you have accumulated and total volume of Bitcoins gain still all of that will be vanished if mishandled also if you don't have other source of income to get when you decide to retire.

So better get a lot of volume as you can then find other alternative which needs less efforts but can generate you a good income flow. What I'm thinking about right now is to buy some properties aside from saving Bitcoin then create a for rent establishment business since we can possibly get a passive income with this option.