Envy is the completely wrong framing, it is about fairness. If you design widgets and 99 people build them and everyone works the same number of hours, then the fair share is 1 % for everyone. One percent of the work, one percent of the profit. If you take 2 % [1] while everyone else only gets 0.99 %, that is unfair. And look, the difference for each individual is tiny, 0.99 % or 1 %, that makes it easy to dismiss despite being the source of the unfair inequality.
He will get the same as the others if he works the same number of hours to run the company. The dept would ideally be company debt and not personal dept, after all one reason to found a company is to separate personal and business risks. But if you invest personal money in the company, you get that money back plus some risk and opportunity premium just as you would pay back any other loan. What fraction that is will of course depend on the amount, premium, and payback period. Just investing some money will not provide you a perpetual income.
[1] 1.99 % if we want to be precise.