It’s a name the community chose for itself. https://en.m.wikipedia.org/wiki/Incel
"Incel" is now widely used as a negative-connotation catch-all term for young loner men almost with the implication that they chose this life for themselves rather than being denied opportunities by society.
The truth is everyone can get laid, and it's not very hard at all. But the pre-requisite is liking the people who you want to sleep with, which is hard when you hate women.