Musk has more than enough money. Apparently, he doesn't even own a house, at least that is what was reported recently. I don't think he has a mega yacht like Bezos.
He does care about free speech, and I think he is looking to improve what is probably the greatest medium to provide news today.
A little over a year ago, if you said the vaccine doesn't help the spread of COVID, it would be censored. If you said cloth masks don't work well, you would be censored. If you said anything about Hunter Biden's laptop, you would be censored. Even the moderate left, like Bill Maher acknowledges this shift in censorship.
I'm all for fact checking, but the tech fact checking has been extremely one sided. We need true discussion of topics that people don't completely agree upon. It's a difficult job to weed out hate speech and deliberate disinformation, but Twitter went completely overboard.
Of course, Musk is looking to make a positive return on his money as well. He seems like a liberal leaning person, but extremely intelligent and sees the danger of the far left pushing their agenda through a narrow group of options of social media.