If you try to dump $100M in shares of VOO (to finance a luxury hotel purchase, say), you'll flood the market and the share price will drop, and you either won't have access to your funds quickly or you won't get all your money back. There simply aren't enough interested buyers for your single security to absorb your giant sell order. This would not be true if you had manually diversified that holding, which is why no one with liquidity requirements holds single securities in anything like that kind of volume (i.e. people do it, but they do it for e.g. corporate board vote share reasons).

Again, though, the point is that while holdings in big funds only hit this level at really obscene order volume, bitcoin sees liquidity problems at something more like $1M orders.