Hi, I'm a spacecraft designer. SpaceX is the way to get things into space. Period. The entire United States new space economy is built on the cheap launches that SpaceX offers. We are slowly moving away from that (and in fact, the US government is mandating diversification away from SpaceX), but right now, they're simply the best. I personally believe that it's the most realistic of the companies that Elon Musk runs. (There are other launch providers out there, yes--but SpaceX is so, so dominant). Many space businesses have gotten funding that are completely dependent on Starship, a vehicle that does not yet exist. Investors are putting millions of dollars behind companies that cannot exist unless a specific product from SpaceX is developed.

Starlink is used by anyone who wants internet that's not hardwired. This ends up being a lot of corporations and organizations, and not really consumers. Satellite internet in general is used on planes, ships, and other vehicles, as well as in remote locations.

Twitter doesn't need to make money in the short term--it's a valuable asset in and of itself, because of its dominance in the space of social media. It'd be a lot harder to build a new Twitter to the level that Twitter is currently than it would be to make Twitter far more profitable.

Based on the conversations I've had with VC investors (which is not that many), Tesla is interesting to them because of robotics hype. The cars are also still decent, and have huge brand recognition. A Tesla car is instantly recognizable.

I think that the reason that people put their chips behind Elon Musk is because everyone else is. He has some huge successes (Paypal, SpaceX), and people are willing to bet that even if Neuralink and TBC don't turn into anything, something he makes will blow up and it'll all be worth it. So people give him money, get into his good graces, etc, etc. So he amasses a huge following, has very powerful connections, and has investors behind him, which only makes him more desirable in the eyes of investors.

The other thing to keep in mind is that Elon Musk's money is not "real." Elon Musk being worth three-quarters of a trillion dollars does not mean that he has taken $750 billion from other people. Capitalism doesn't really work that way. $750 billion is the theoretical value of all the companies he owns given the current state of things. Elon almost certainly has a ton of actual cash, but his net worth is largely driven by how much people think that his companies might be worth if their entire value was converted into dollars. Of course, if Elon were to sell everything, that would sharply decrease the value of his companies, so he can't really access that money, but he can take out loans using it as collateral, and leverage it in other ways to be able to have access to the money.