There's fairly low overlap between aerospace engineers and software developers. People that want to build jets and rockets don't tend to transition to enterprise SaaS development, regardless of the pay gap.
At any rate the biggest reason Boeing salaries are lower is because they are the only competitor. The reason why silicon valley companies pay so much is because they're all competing for talent and the talent has optionality to go down the street and get paid more.
SpaceX is a private company so no, the stock options are not the biggest pull there. Hiring may be easier due to strong leadership but that goes without saying.
At any rate the biggest reason Boeing salaries are lower is because they are the only competitor. The reason why silicon valley companies pay so much is because they're all competing for talent and the talent has optionality to go down the street and get paid more.
SpaceX is a private company so no, the stock options are not the biggest pull there. Hiring may be easier due to strong leadership but that goes without saying.