It's also not mutually exclusive. I can and do give away huge sums until those taxes go up.
I'm buying land and putting it into conservation, giving to community land trusts, and other ways that essentially make permanent changes towards the world I want to live in.
One person giving away their money just means they don’t have the money and society still doesn’t have, say, Medicare for all. It takes a collective effort to get the collective gains we need to see.
There's a coordination issue here. I'm astonished that so many people fail to see it. The result of one person donating $600k to charity / the treasury is completely different than ten thousand equally-wealthy people all paying $600k.
This person is saying "I will cooperate in a prisoner's dilemma, if and only if I can arrange a binding agreement by which others cooperate too", and a bunch of people are replying "then go ahead and cooperate; let the rest of us be free to defect"!
(By the way... uh... what do you do to earn $750k? As someone earning about 1/20th of that amount, I'm curious for some pointers).
The original poster clearly defined the terms that they would be willing to pay extra taxes. The user I replied to ignored that and said "give it away". The comment was obtuse.