this could turn into a political debate quickly, but I'll try to avoid that. The benefit to a free market is that it's self-policing. If you truly are a greedy, evil, law-breaker, the market will put you out of business much faster than any government could.
If it wasn't for flippers/rehabbers, think of the enormous amount of vacant and vandalized homes every town would have. Everyone knows that vacant homes lead to squatters, drug dealing, etc. So who is really the evil person in this situation? The investor that is essentially reducing crime and being paid for their time, effort, and risk? Or the person that scolds entrepreneurs for providing a service because they feel the investor made "too much money".
As a side note, it always amuses me when I hear people talk about how their boss is making "too much money" off their labor but then demand a raise for no extra effort put in.
Lastly, congrats to you, Bryan, on a project well done, you awful capitalist.... Look at you providing a nice home at a fair price, it's disgusting... (sarcasm)