I've yet to see Elon doing something with his stock value that seems very wasteful.
He looks to always reinvest it in starting new companies. Which means the stock value is doing good work that benefits everyone since the new companies are worthwhile in nature. Sure, you could argue that he should sell his stock and use it to cause more direct and immediate help, but you don't have the money he does, and he seems to want to make a longer term, high-risk, high-reward type contribution to society. Which is his choice and might actually work.
You could argue Cybertruck was a waste of money given it isn't selling very well, which is fair, but if you were him you might also want to spend a tiny fraction of your wealth to design a car styled in exactly the way you want it vs what marketing says will sell. I wouldn't hold that against him too much. Everyone is allowed a small side project that might be a bit pointless or not very profitable.