What you’re missing is that these others you quote are in fact NOT doing ok, you’ve done the calculations and can’t see how they’re making money, the answer is that they aren’t, they’re dying a death by a thousand cuts but are plodding on because even if they walk away they’re saddled with thousands of pounds of debt, the ultimate catch 22; can’t afford to trade, can’t afford not to.
If you’ve got money to burn buy three houses and rent them out. I 100% guarantee you’ll see a better return for your money. If you are insisting on spending money in transport then you need to specialise and find a niche market. Have a look around at the work nobody else wants to do, ask yourself why and then think of a way to make it profitable for you to do it.