We've had these for ages and Elon has not made any advances in tunneling technology despite hundreds of millions of dollars and however-many years invested.
> 4. Elon Musk and his Flamethrower
Elon Musk and his $500 roofing torch.
> Elon Musk and his Self Driving Car
Elon Musk and his moving goalposts...
Of course, there is also "Elon Musk and his Cult of Personality", which is how he can slap a brand-name on a roofing torch and get people to run around calling it a "flamethrower", and how he can get away with calling a system that still requires human supervision "feature-complete full self driving".
This also contributes to his being able to get away with publicly calling an international hero a pedophile, just because they had the gall to question "Elon Musk and his Cave Rescue Submarine".
I give Elon a lot of respect for what he has done with 1 and 2, but I think his visions would be better served by less hero-worship and more serious people holding him to account.