But if wealthy people really want to use a crypto they could easily private fund their own and basically have an OPEC style crypto - only big boys at the table. It might even exist now for all we know.
I'm a little dubious that it would be that easy. If it were based on the same algorithm as bitcoin, they would have a very hard time securing it. (bitcoin hashrate will completely dwarf anything previously imagined before the end of this year)
even if it's a completely closed-source project, (and it would presumably have to be, if you want to limit participation to "only big boys") all it takes is one person involved to become compromised and it's game over.
Perhaps it would be possible for these very wealthy people to use some kind of private ledger to "keep score", but unless the ledger is open and verifiable, the accounting of transactions is susceptible to fraud.
In the end, I don't think it's feasible, mainly for the reason that 99% of the "very wealthy" got to be in that position by leveraging the current debt-based system against the "lower classes".