Put one gallon of diesel or jet fuel into a 5 gallon gerry can. Put it outside in the desert, in the sun.
Then shoot it.
From a distance.
Be ready to be very, very surprised.
Well, sure, if you can get enough of it to evaporate into an enclosed space.
That’s why it’s used as a combustible fuel.
But pouring it on a small flame will put the flame out like water. I speak from personal experience. I’ve found that if I really have to get something going, I mix a little gasoline (and it doesn’t take much) into it.