If he was able to exit his Twitter stock position after the jump in price he created it would wash out the $1B.

If he exited TSLA to the tune of the remaining $10B or $15B, staving off a 50% decline in that value then he came out way ahead.

It seems very likely to me he will find a way out of the $1B fee and end up settling for some fraction.

Of course if he just borrowed against his TSLA to facilitate this deal, as I have read he did, then his profit on the move depends on the terms of the loan.

The $1B termination fee is the tip of the iceberg. Changing your mind is not covered in the termination clause, and his evidence Twitter mislead him is contradicted by his own statements prior to the deal. Twitter is owed substantially more than a billion. Likely closer to ten.

He sold something around $10 (+/- 2) billion of Tesla stock. The loans don't matter as they were (a) tied in to use only to buy Twitter and (b) allowed to expire last month.

Sell $40b of Tesla without causing a dip, is worth a lot more than $1b. A 3% dip from news he's selling that much stock would cost way more than $1b.

It's not just the potential impact upon markets. Shareholders of that size have legal obligations as well. If you own that much of a company you are specifically and legally precluded from selling it all at once in many circumstances. Bill Gates could not sell his entire Microsoft stake all at once back in the day into an open market as it might cause the security to drop significantly and for other, legal reasons. Certainly, the securities exchange act of 1934 requires disclosures of certain sales of shareholders above a certain percentage of shares of publically traded companies, but also more nuanced and exacting laws regarding national security interest prohibit the sales of securities and ownership to specific parties or foreign interests. When the scale of your ownership stake is in the billions, that certainly limits the potential buyers of the entire stake to a short list.