Why does a profitable public company, for example, continue to sell shares and accept more and more investments? Because they want to have even more profit I guess. I cannot answer for the motivations or internal mechanisms of the company.
And in a sense you are partly right, I'm not saying no. I repeat that I cannot assure you of anything. However, we cannot call everything that makes good profits a scam. 5% or 7% a year are centralized bank level earnings. That is simply theft, because that bank is making a lot more money just by having your money in it. And it's practically not giving you anything.
It cannot scare us when we find a business that gives higher profits. And beware that I am not talking about doubling or tripling your money in 15 days, that is clearly impossible.