Don't forget that he is a businessman, and he is also the richest man in the world. If he were stupid enough to sell his fortune at a loss, he wouldn't be the richest man on the planet.
There are 2 mistakes I see here:
1. Even the richest can lose now and then, usually they take small loses to avoid bigger ones or to make a much better business soon afterwards.
2. Tesla is not only Elon Musk. I expect there's a board that take decisions and those decisions may or may not be influenced by what Elon Musk wants.
Based on price averaging, it can be inferred that Tesla lost money in the most recent bitcoin sale, but we don't have specific data for their bitcoin buy orders so nothing can be confirmed.
Yeah, this sounds more like it. Either there was no loss at all (as @Rikafip already said), either the loss was smaller than the previous gains.
Twitter is, again, unreliable.