Okay, let's think of a scenario and analysis what will happen if we have a fixed supply token as a currency. Let's think BTC is the world currencies now. In these cases, rich people will buy as much BTC as they can and took them out of circulation. Poor will have little chance to buy any BTC. When most of the BTC will be out of circulation price of it will go out of reach of normal people. The whole world will be in an economic crisis and violation of the law will be common because people will not have any BTC to buy food.
But that doesn't mean crypto can not be one of the world currencies.
What you have in that case is a very very high price of bitcoin, people who could still buy a few satoshi at the very least (you can't have 1 satoshi equal to 1 dollar, that’s too much) and we are talking about other coins as well, which will mean people can get included due to altcoins. Most of those coins are either limited (like btc has 21 million cap) or they are unlimited and we get to mine or stake them as well so it’s not all rich people.
So, in the fiat world rich people have billions and more billions gets printed ended up in their pockets whereas our small investments all become worthless in the long run. I do not see that as a good way of making money to be fair, I believe that it is a very difficult way to make money for wealthy people, they would lose out in the long run. Imagine the fact that there are more than 21 million millionaires in the world, so not even all millionaires will have 1 bitcoin.