The share is under your control, the money isn't. Being able to convert it at will doesn't change that. Also how much if anything it's worth when you go to convert it isn't under your control either.
And that doesn't change the fact that Jeff Bezos, fundamentally, is extremely wealthy, even if he'd have to sell or borrow against a few shares to use it.
It kind of was the subject. The person I replied to up thread was clearly implying that rich people making investments is a net benefit to everyone, and if they were all acting like VCs, maybe, but since they are mostly locking up their investments in mutual funds or real estate, its less clearly beneficial.
Yes, a lot of economic activity is predicated on the availability of investment capital, but only investing in already-successful firms doesn't generate new economic activity. And static, unused real estate generates basically none at all.