It's a lot harder to just spin-off and "build your own stuff" in hardware though, which is I think what keeps the "married employees" around longer. The startup costs are much higher and riskier. And you need a lot more people. Building that rocket engine from scratch probably required around 50 - 60 people to really get it all together.
Also, a rocket engine is a core feature of a rocket (literally cannot fly without it). If they started development of this engine in 2018, that's *six years* of work to get to their current state. Imagine spending 6 years on a core feature of an app that you'd consider "min-viable", and everytime you had a bug the computer you compiled the code on spontaneously combusted?
This was one of the main reasons why I didn't have side projects for a very long time. My day job was fun, and it scratched every itch I had. It was such an expensive project that I knew that I simply couldn't afford to do anything that would excite me that much, so I threw all my creative energy into the job.
Eventually though, it became just a job, as it always does. And then the gaze turned elsewhere, looking for more enjoyment and satisfaction.
Also, a rocket engine is a core feature of a rocket (literally cannot fly without it). If they started development of this engine in 2018, that's *six years* of work to get to their current state. Imagine spending 6 years on a core feature of an app that you'd consider "min-viable", and everytime you had a bug the computer you compiled the code on spontaneously combusted?