1. You're typically working on small teams with some wickedly smart people around you. Very, very few dummies or under performers at his companies. Definitely a community feel where you know everyone in the spheres around you. Also, everyone wants to help you, and so you tend to respond in the same way back to others.
2. You get to question everything, and the first answer is often not the right answer but you have to actually use your brain to get to the right answer. No inactive listening, even when you're getting feedback or asks from execs.
3. You know what the North Star is, and you're laser focused on it. If what you're working on doesn't build toward that mission, you're encouraged to speak up and question it, no matter where you are in the company. There are generally no rules for who you can and can't talk to.
4. He pays the most attention when things aren't going so well. If you and your team keep a tight ship, keep up with the (fun) timelines, communicate out well, and grow and learn appropriately, things will tend to go smoothly. Not always true, but it tends to be.
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The Twitter situation totally sucks, and I empathize with everyone impacted, but I think Elon is working to bring the style that is proven to work for SpaceX and Tesla over to Twitter. There are definitely growing pains to switch to this model.
If you believe in the stated missions of each company, and think your work will do a net good for yourself and others, then it's a no brainer to want to work there.