(And effective altruism is a scam designed to lend a thin veneer of credibility to naked greed)
People want to go after billionaires because the common misunderstanding is that there is a limited supply of money/wealth, and the billionaires have “hoarded” it all and made it unavailable to everyone else. And, there is jealousy.
As you say, I agree that generally the net worth of certain individuals has no bearing on anyone else’s life or fortunes except for
1. the positive economic impact (e.g. billionaires spending money),
2. the positive tax and infrastructure impact,
3. the positive impact of donations to nonprofits, or
4. the potentially negative political impact (e.g. billionaires sending money to politicians) if one is aligned with a different political ideology.
Generally, a large yacht parked in the harbor or an expensive sports car on the highway does not affect anyone—-it just makes them feel bad.
Why do you bring up the French Revolution? That was mostly an uprising against the aristocratic Ancien Régime of France. Meanwhile the fabulously rich actual capitalists over in England were fine, and stayed fine; never a revolution there.
Did they fear a French revolution style ending to their greed?