Not much different from other 'desirable' industries.

e.g. entertainment

Lots of people may want to "work on space", but many (most) can't. This isn't unskilled labor we are talking about here.

Honest question: of the folks who have the necessary skills, aren't many of them working in low-paying academic jobs?

From the outside, it seems like moving to SpaceX would give them an opportunity to put ideas into practice while making more money than the average post-doc.

Not many people want to work on legacy insurace company backend systems, but those who do aren't necessarily unskilled labor. Many of them would rather work on space and would accept a pay cut to do so.