This seems to me to be a case of simple betterthanyouism. The artists (and gallerists) see themselves as preserving the public good, encouraging collectors to hold onto artworks and eventually donate them to Museums. The collectors see themselves as, well, collectors. And like any other collector they claim they should be able to buy what they want and sell it when they want. Ok. Good.
This is true-ish in both cases. But the counter-claims (of pure and simple profiteering) are also true, and seem, to my mind, far more reasonable explanations.
But I’m not a multi-millionaire. I’m not a gallerist.
I’m merely a jilted art lover.