Actually no, I'm personally NOT for the debate that Bitcoin should have a hard fork to change the supply cap. I believe that part of the protocol is ossified. I'm asking "what is the threshold", a question/topic that's admittedly a difficult issue. To put it in an extreme situation, if 90% of Bitcoin's supply was under the custody of a cartel of 10 asset managers, could it be said that Bitcoin has failed?
To put that in context with this topic, if truly twelve of the twenty largest banks and asset managers truly want to accumulate as much Bitcoin as they possibly can, then $500,000 per Bitcoin is not really that high.
Let's imagine that your assumption is realized. A few funds have taken and concentrated in their hands almost all bitcoins, because they decided that this is a good investment. As a consequence of this decision, bitcoin will practically stop moving, because it makes no sense for them to sell it, this is a long-term investment. In the absence of movement, miners will no longer be interested in it, difficulty will drop, the risk of a 51% attack will increase, trust in bitcoin will decrease, bitcoin will start to drop sharply in price, and investments in bitcoin will depreciate.
If some random dude on the forum managed to see this scenario over a cup of hot drink, then the analytical departments of the funds are also quite capable of doing such analyzes. Accordingly, no funds are interested in buying up and hiding all bitcoins, they are interested in participating in the development of bitcoin, but within the limits of not depreciating the asset in which they invest. If they have large enough investments, they may well take an active part in the circulation of bitcoins.
So I don't think the problem is realizable.