Liquidity is an irrelevant side issue. Gates would have exactly the same problem if he tried to sell all that microsoft stock to buy turnips; he could destroy billions of dollars of wealth just as easily as the people you so despise. (In fact, if you turn it around, Gates doesn't really have 100 billion dollars. He has something that looks like it's worth that much, but only for as long as he doesn't try and use it. If you destroyed 99% of his shares, you wouldn't be destroying any actual wealth - Gates' life wouldn't become any less comfortable, and microsoft would still exist and still be making the same products. So you're not damaging the societal wealth at all).
The interesting question is who will make better use of the dollars, or indeed microsoft shares. And the available evidence is that the poor make much more efficient use of their money than the rich (indeed on some level they have to, because someone 1000x as rich as me certainly isn't getting 1000x the value from their money). They spend money rather than hoarding it, improving the economy, and each marginal dollar improves their lives much more than it would for a rich person.
The interesting question is who will make better use of the dollars, or indeed microsoft shares. And the available evidence is that the poor make much more efficient use of their money than the rich (indeed on some level they have to, because someone 1000x as rich as me certainly isn't getting 1000x the value from their money). They spend money rather than hoarding it, improving the economy, and each marginal dollar improves their lives much more than it would for a rich person.