There are exceptions but the weight of statistics is against your thesis. I think it is a better argument that people with higher debt to income ratios experience poorer outcomes than people with lower or no debt to income ratio.
Statistics are so easily manipulated they are almost meaningless, you should know that.
I know plenty of wealthy people who have never borrowed a dime in their lives. I also don't know of anyone who has gotten out of debt and thought to themselves "I should go borrow some money to become wealthy." I'm sorry, it just doesn't work that way. I can also guarantee that the folks who have borrowed money their entire lives to 'make money' have had a much more stressful financial life than those who have done it without debt (whether they admit it or not.) Add up the interest someone pays throughout their lives running both their personal and business affairs on credit and the amount is staggering, often in the millions.
I used to borrow money, not anymore. I was being 'responsible' in my borrowing, only borrowing to 'make money' as you describe. Things like equipment for my business and farm, using a credit card to purchase parts and supplies for the cash back, etc. After paying off my equipment I quickly realized what a burden that took off my business. My overhead was much lower along with my stress level. If I didn't work for months I'd still be ok, I could be more selective in the jobs I took, no more worrying how I was going to make all the payments. All that money that was going towards payments started going into savings and investing instead.
I haven't missed any of the supposed perks of being in debt or having a good credit score. I still can get utilities and rent equipment, just have to provide good references and talk to someone in the company with half a brain. I quickly found that by not paying for everything with a credit card I would often save a lot more than the cash back. Most of the gas stations around here off 3-5% off if you pay with cash or check instead of credit card. Same with some of the parts houses I deal with. In fact you'd be surprised at all the places that will give a 5% discount if you pay with cash if you just ask. They say they'd rather their customers get the 5% than the banks/credit card companies. Saving 5% is a lot better than making 2% cash back. Online purchases are no problem either using a Debit card through our local bank. Run through the Visa system is has all the same protections as a credit card.
Another misnomer is being able to write the interest off on your taxes. To keep the numbers simple lets say one paid $10,000 in interest over a year, lets also assume a 35% tax bracket. So, you are going to pay the bank $10,000 to avoid paying the IRS $3500? Seems like a waste to me, I'd rather keep that extra $6500 I made.
Buying land or a home is one area where you may need to get a mortgage. Even without a credit score this is fully attainable. We got our home using owner financing, made a good impression and on-time payments for a few years then got a traditional mortgage based on our history. There is still such a thing in this country known as "manual underwriting" of a mortgage, although it takes a lender who knows more about banking than just reading a credit score. You won't find this at any mega bank, but a lot of small local banks, agricultural banks, credit unions, and a few traditional mortgage companies will still do it. If you have paid everything on time in your past, have good references, a steady job and income and no credit score (no credit score is much different than a low or bad credit score) there is no reason why someone can't get a mortgage through manual underwriting or an in-house loan at a small bank.
The way to become wealthy is very simple and it doesn't include debt:
-work hard
-live below your means
-save money every year
-invest wisely