I think you're probably wrong. Plumbing scales like any services business: you stop being able to manage your inbounds, so you hire another plumber who makes less than you. Repeat N times. At some point, you're making enough off the top of all the plumbing work to stop doing plumbing; now you're a full-time business manager. You brand, promote, and scale --- by franchising, hiring more managers, partnering, or securing large contracts. Somewhere in the middle back there, you became a millionaire.
What is also probably true is that it is very hard to go out of business as a freelance plumber. It is very easy to go bust as a tech entrepreneur. The flip side of that: on a steady income, the plumber gets more opportunities to grow her business than the tech entrepreneur --- she can stay in business, turning different knobs, indefinitely. You hope that the tech entrepreneur's individual opportunities are much more valuable, but that depends, doesn't it?
There's also the classic factoid that most millionaires got there not by striking gold, but by managing their money well.
Be careful about Geek Exceptionalism. It will burn you. People excelled in business long before there was an Internet.
My point was that it is possible to become a tech millionaire in a couple of years - this is of course unlikely - but there are many examples of people doing this. It's almost impossible to become a millionaire in a couple of years as a plumber.
Whilst like you can do the process you point out, it's likely to take 10+ years to do that. You could also do this same process as a tech consultant and then grow your consultancy business the same way - but that wasn't my point - that's all.
People after all play the lottery every week - though on average they would be better off putting that money in a savings account and waiting 30-40 years...
What is also probably true is that it is very hard to go out of business as a freelance plumber. It is very easy to go bust as a tech entrepreneur. The flip side of that: on a steady income, the plumber gets more opportunities to grow her business than the tech entrepreneur --- she can stay in business, turning different knobs, indefinitely. You hope that the tech entrepreneur's individual opportunities are much more valuable, but that depends, doesn't it?
There's also the classic factoid that most millionaires got there not by striking gold, but by managing their money well.
Be careful about Geek Exceptionalism. It will burn you. People excelled in business long before there was an Internet.