I think after the next bull run only institutional investors will be able to hold a full Bitcoin. The price will be out of reach for most of the retail investors.
I think we’re already there for most people. I don’t have any friends who hold anywhere near 1 BTC. Most people don’t even have that amount saved for retirement or invested in equities. If another bull run does take us to six figures, you are probably right that the only holders left will be extremely wealthy individuals and investment funds.