> why do you trust him when he does it?

His companies have made many monumental engineering achievements at his direction.

His companies making those achievements is not the same as he personally making those achievements. He does have some talent in being a CEO of a company and inspiring employees and investors.

But also don't oversell that: only Tesla and SpaceX have been successes, and he's had to have them bail out is other failed companies: SolarCity, Twitter, and xAI. The Boring Company also doesn't seem to be particularly successful either, and he never got around to building a company to build Hyperloop in the first place.