We should tax the shit out of them, if only to reduce the unelected power their wealth buys.
Just like we should tax the shit out of the non-EA ultra wealthy.
We can have a democratic society or we can have the concentration of great wealth in the hands of a few. We cannot have both.
And they support raising taxes because it's a good way to signal that you're "for the people" and cheap if you care about power more than money. A billionaire CEO will stay a billionaire if their income tax is 90% and unrealized gains tax same as their portfolios growth, and stay a CEO even if they go broke.
The important part for them is power over other peoples lives because that's exactly what you need if you believe you're a special "rational agent" who is responsible for pushing humanity in the right direction. That power can come from shady think tanks, government jobs or controlling a trillion dollar company.