Because of the value of Bitcoin, people will hoard it,
Take me as an example. I will invest 20% of my salary in Bitcoin because I think Bitcoin is very valuable and I believe in Bitcoin, so I think Bitcoin is worth investing in.
But if you let me buy something with bitcoin, I will hesitate and pay with fiat currency first.
Although people can pay in any way, will Bitcoin be your first choice?
Now the difference between fiat currency and Bitcoin is that one is inflation currency and contraction currency. Inflated currency (fiat currency) means that if it inflates, you want to get rid of it as soon as possible. For example, we use fiat currency to buy things, invest in real estate, cryptocurrency, stocks. And to shrink the currency (Bitcoin) you buy goods or services, or hoard it. This has no effect on the economy, except to reduce the monetary base and make the currency more scarce, so deflation is faster.
In my opinion, Bitcoin is a store of value, not a currency. There may be cryptocurrencies becoming legal tender, but not now, volatility and supply and demand need to be considered.
hodling bitcoin is a good idea than spending it to anything.. Because bitcoin is a very promising crypto in the market so if you keep spending it, and when bitcoin price were gradually increasing of course you will receive less profits from it. So you better pay with fiat than spending your bitcoin because it's like it's ok for you to miss the opportunity instead of good profits.. So always think about it if you want to buy something especially if it's unnecessary.
