When someone does something to “Set the world on fire” it means they did something outstanding like create the best thing since sliced bread. The problem I have with this saying is that setting the world on fire is NOT a good thing. Turning the Earth into a giant raging inferno isn’t exactly a positive accomplishment. That seems more like an arsonist’s greatest fantasy.
Maybe this saying is what’s to blame for climate change. Human beings wanted to “Set the world on fire” so we started burning more and more coal and fuel into the air altering the atmosphere and strengthening the Sun’s effect on the planet. Setting the world on fire is just stupid. You’re going to melt the ice caps and drown everyone. At that point, it doesn’t matter what you did to excite people so much because we’ll all be drowned corpses. The next time you come up with a great invention just say it’ll “Drown humanity.” That makes about as much sense as saying it’ll “Set the world on fire.”