They feel great, because he just magically turned a ~50% loss in Twitter into a ~50% return in xAI and a ~0% loss in Twitter.
Of course, you can't buy $20B worth of mangoes for $40B worth of Mango Holding Company stock and then suddenly make your mango-holding business worth twice as much money.
But you can pretend!
Private valuations, especially VC-funded companies, have been nonsense for decades. Elon is just exploiting that egregiously.