Hello. Yes you can make money with ue4 but you just have to make a game or tools for game development that are highly sought after. Single player story games dont usually make a ton of money for long periods of time, but mmorpg games will maintain a constant cash flow as long as you continue to make DLC. Think of popular single player games that would be fun if made massively multiplayer, such as super mario galaxy or kingdom hearts. That should send you in the right direction.