I wondered this early on. More so when I thought he would actually buy twitter as Twitter had had some serious share price decline at that point for over 6 months, so it's a way to shift money from an inflated area to a more moderately priced one. Plus he obviously likes the platform in general.

If true, I don't think it's the case he did it intending to pull out. Seems unlikely he would have signed the billion dollar exit clause when he could have easily dragged the initial talks on a bit longer for largely the same result before 'changing his mind'.

My best guess is the offer was genuine (thought impulsive) but as he's seen the price drop further, now his offer seems too much. Why pay $44bn for a sub $30bn company. Kinda simple but seem most likely than all these more complex theories.