Can you trust anything Musk says? We know he’s full of shit; ask Thiel. As for the real reason, pick your poison:

- He purchased it because he’s in a right-wing filter bubble and bought into the idea that Twitter is controlled by a secret left-wing cabal and genuinely believes he’s doing the world a favor because he thinks right wing propaganda is actually moderate

- He has the same brain damage as Trump and requires adulation by sycophants and he thinks this is the best way to guarantee his fix and give him control over his critics

- He wanted the brand name and doesn’t care about what services are currently offered under it

- He’s from the southern hemisphere and wants to destroy the social fabric of the United States

- Some permutation of all of the above

Not sure which of these are the truth, but I’m guessing a combination of the first two.