Because Effective Altruism doesn't mean what it sounds like. It's a pseudo-ethical philosophy that justifies gross accumulation of wealth with the implication that at some point in time you will use your wealth to do good. The poster child for this is Sam Bankman-Fried, the scam artist CEO of FTX who conned investors into believing he set up a securities-backed cryto-exchange, when in reality the securities firm insuring the cryto was being inflated by the cryptocurrency it was allegedly insuring.

SBFs fall from grace should have killed any legitimacy Effect Altruism ever had, but unfortunately there are billionaire sycophants trying to bring it back to life. I guess the reasoning is if there are that many idiots that keep falling for Donald Trump's promises, they should be able to find enough idiots in the investor class to keep running the same scam over and over.

It wasn't, in the hands of the philosophers who came up with it. Then it was coopted by silicon valley nutters and now it's basically an excuse to self serve, while claiming the moral high ground, for techno feudalists.

It’s name washing. Carnegie was a horrible person no matter how much his foundation funds classic arts.

It lets billionaires answer "Why aren't you helping anybody with all your money? Why do you need even more money?" with "Oh, I will, but I haven't started yet, because I'm an effective altruist!" and not get immediate scorn.