Doing things in order to benefit solely yourself and disadvantage innocents is wrong, period. Sure, a guiltless person achieves their goals more readily, but at the end of the day, they are alone. No matter how many people they surround themselves with, they can never show their true selves to others, because they KNOW inside they are appalling, and they can and will burn every bridge they come across if it suits them, and eventually, people catch on to that. They lead hollow lives. You should be proud that you have some standard of morals, and not that you're being held back by being a "good person", that you have something inside of you telling you to do the right thing.
Don't be an starfish, and if you ever are, apologize, they're not hard rules to follow. If anyone is having trouble with that, I don't think I can say anything to help you that hasn't been said to you before, by someone much smarter than me.