It’s also possible to steal items from grocery stores without paying for them. If you don’t get caught, it’s free!
Also, think of all the free cars that are parked at the side of the road, and all you need is a forklift to lift them onto a flat bed truck and you can take them home!
Given that the engine can be downloaded by anyone, and you could conceivably just “forget” to tell Epic about your sales, there’s obviously a bit of honor system involved, where dishonest people can hide in the dark corners.
If you do this in the US, and you have a reasonably successful game where Epic will discover you, you’ll likely have to pay more to the lawyers to defend yourself from the lawsuit, than it would cost up front just to give Epic what they deserve.
I’ve learned that it doesn’t usually pay to worry about all the bad things that COULD happen; instead focus on making sure the good things DO happen!