I agree with you that we have become afraid of a scenario that has become very likely, which is that Bitcoin will become a tool of control, despite its decentralized structure. A limited number of Bitcoin units makes it a scarce value, and everyone will seek to own it. With the expansion of individual ownership, Bitcoin will become a store of value, and those who own the most will be able to control the supply and demand market. A decentralized design does not mean decentralized use either.
I wouldn't say that they are going to control the supply and demand market, as this is close to manipulation. And we have heard this before, that a large whale could manipulate the market but we haven't seen any proof yet.
So as far as entities goes, it's the exchanges, casinos, and personalities like Michael Saylor who might have a huge bag but it doesn't mean that they have total control. For me it is still us average joe investor that makes up the most of it as some of us could be in the market for so long already.
of course they do not have total control since a huge part of bitcoin is still distributed among different people all over the world but if they manage to own more than half it can be a point of worry since they can just easily dump all of what they hold and affect how bitcoin is valued even if this happens i would always have trust in bitcoin to bounce back and for bitcoin enthusiasts to come and buy when the price drops