@Lydie It's not possible for Elon to buy it for many reasons.
First off there's just... nothing to buy. There's nothing that would give him control of the network. It's fully open and the second he bought any part of it, people could just easily start up another copy of it without his involvement.
Second, the company isn't for sale and would never sell to him even if it was, because they are extremely opposed to him. The CEO of bsky demanded total independence from Twitter for a reason.