Because it shouldn't come with the same compensation as any other day job.

Let's say you can make $80,000 as a hairdresser. You are seriously proposing that someone who takes all of the risk of

* Renting their own hair salon,

* Building up their own clientele,

* Taking out loans to purchase hair dressing equipment, and

* The thousand other things the business owner has to do in addition to actually dress hair themselves,

should walk away with the same amount we the person who just gets hired to dress hair.

No one would ever start a legal business under such a regime. It's all downside! Which is why you never see people actually owning and running businesses (successful ones at least, and most unsuccessful ones too) with the mindset you describe.

Do they actually walk out with more, though? Looking at the 'businesses for sale' listings here in the UK, I can see most of the hairdressing salons have an asking price of between 2x and 10x the statutory minimum wage. So even if the hairdresser built the business by themselves in only a few years, has never sold any stock, and has no outstanding loans, they'd probably get no more than twice what they'd have earnt as a non-entrepreneurial hairdresser over the same period. Then that will also be taxed at a higher rate.

I'm not saying that being an entrepreneur isn't a good way of making money in certain circumstances, but I think that starting any brick-and-mortar business is barely viable compared to persuing a white-collar career where one's final salary would dwarf the value of even the most successful hairdressing enterprise.

TLDR; the promise of money alone cannot motivate someone to become an entrepreneur.