Go on any incel echo chamber and you'll know.

The word incel has evolved beyond its literal meaning to refer to a specific subset of people.

Also I may be wrong here - but I think the term originated as a self-designation by a group of openly misogynist men? So even when the term originated it would have had that connotation.

Either way, there's a big difference between someone who can't get laid an an incel, even if the terms don't reflect that difference.

the internet is a dumping ground for suppressed frustration

You won't find a genuine answer in these comments. Incels are hated because you can easily make up excuses to.

I think theres what the word actually means, and then theres the stereotyped version that maybe has more power, ie angry about being celebate, poor mental health, usually hates women because of it.

Perhaps involuntarily celebate and incel mean slightly different things to each other by now.