7 figure personal income for the owners of a services company is not unheard of.

The owner might elect to keep money in the business account instead of transferring it to a personal one for tax reasons. If you are fully in control of the business there isn't much difference. For example you can buy a house with company money and lease it to yourself for $100/month. This would not register as profit for you or the business.

That all sounds widely inaccurate from my experience. It's just pass-through income, it was even addressed in the recent tax overhaul. Additionally, a requirement for rentals (or check at least) is whether it's being rented at the current market rate.

Depends on your margins & efficiency. I was charging $100/hr & paying $20-$30 (which wasn't a secret to anyone, clients or employees). But it was hard to save because I needed automation I didn't have, and paying for it was not tenable for internal reasons. Eventually I sold my stake for a modest amount and became a software engineer. I decided I wanted to have the option to automate.