The thing about a profitable business that is different from a tulip is that it can at any point decide to issue a one-time or ongoing dividend. It can sell off parts to create cash. It has lots of optionality. Public companies have even more liquidity, which creates more optionality.

Even if you don't have immediate liquidity, it would obviously be worth something to have a slice of e.g. Rolex SA. That's obviously different than owning a tulip.