What's stopping you from doing this since it's incredibly lucrative?

I mark it up. I am a builder. The point is, you need to bring measurable value.

This works up and to the point where people can't afford it (largely due to rising interest rates). Construction/remodeling is still in insane pricing mode right now. The bigger companies will string it out by offering financing but even that is limited again due to interest rates.

Tech companies are structurally different to the plumbing/building business, you can't make this comparison.

Plumbing and building have static value. They will always do the same thing. The value of code is highly dependent on the context. SWEs are highly paid because they can create systems which can be reused and built upon over time.

Hiring an engineer to build a system doesn't make sense when it handles $0 in GMV, but makes a lot of sense when it handles millions in GMV. Tech companies are asymmetric bets.

If we assume a 50/50 split with the helper, and we assume that he can do one of those jobs every day of the week, then his GROSS receipts are only a little under twice my post-deductions cash NET. When we include my stock and bonus and factor in his costs and taxes, it looks even worse for the plumber.

It's good to know that plumbers make decent money. (And they SHOULD make much, much more.) But I will stick with programming for as long as I am able to.

Plumber does not do 50/50. I'm not kidding, the helper could not speak any English. And now, I end up explaining it. If you don't bring measurable value, you are dispensable regarding of HR speak.