Money should make them less vulnerable. They can lose their job, be blacklisted, whatever, and still be fine. Not like the ordinary person where this would mean homelessness.
If they’re vulnerable, it’s the psychological need to keep adding to their pile of money that does it.
That’s not quite right. An administration like Trump’s can destroy people and companies if they really want to, and that’s the threat they’re using to get their way. Openly defying that is taking a big risk - for the targets, it’s not about “adding to their pile of money”, it’s about not losing much of what they have.
Keep in mind that “money” is not some sort of concrete thing like a pile of gold - it’s dependent on factors like the value of companies. The wealthier someone in the US is, the more their wealth depends on their ultimate cooperation with the prevailing powers.
They could lose 90% of what they have and still be comfortable for the rest of their life.
And the only reason their money depends on factors like the value of companies is because they want to add to the pile. It could literally be a pile of gold if they wanted it to be, that's just not the best way to make it grow. More realistically, it could be invested in index funds or something similar that the administration can't selectively destroy.
Worst case the government finds a way to confiscate everything, or imprison/kill them, in which case they're exactly as vulnerable as a normal person.
If they’re vulnerable, it’s the psychological need to keep adding to their pile of money that does it.