The problem is money. Implementing the bad idea means there won’t be money for the good idea. The bad idea also gains inertia, so it tends to stay around and worsen for decades (e.g. current auto-centric infrastructure).

Exactly! I'm Indian, and am tired of listening to the argument that India shouldn't build bullet trains, as hyperloops will obviously be real in 5 years. People think that hsr which will cost 80 billion dollars will be replaced by a maglev in pnuematic tubes for only 6 billion.

There's something of value to the energy and enthusiasm that Elon seems to be able to generate. Even if the initial version of the idea is dumb he may be able to iterate it until it's not, if he's creating more buy in and excitement than everyone else.