Yeah if you want to be pedantic he may not strictly fit the dictionary definition:

Someone who grifts is a thief, but of a particular sort: they illegally obtain money or property by means of cleverness or deceit, and do not usually resort to physical force or violence. A grifter might be a pickpocket, a crooked gambler, a scammer, or a con artist.

But generally language used in regular conversation, like this, is colloquial, not formal. And he firmly fits the colloquial use of the term, as described by urbandictionary:

A money-making operation that is either dishonest and takes advantage of people, or is simply a cause of annoyance or scorn to those who pay. Typically, a grift is a source of easy money to whoever runs it.

He is dishonest by pretending to align with socialist ideals while hoarding money, to the extent of buying oversized property in what is probably the 3rd or 4th most infamously-expensive place in the country. He could've donated that money to help the people he claims he wants to see helped.

He takes advantage of people by selling them the false image of him as a progressive / socialist, when in fact he only is to the extent that it benefits him.

It is a source of easy money to him.

He's what you call a "champagne socialist". I have no respect for such people and don't think anyone else should either.

Besides that, there's no healthy reason for you to be this invested in defending a streamer. Politics should not be a cult of personality if you actually want to achieve anything.