Male incels are generally very miserable people with a lot of mental health struggles.

The implication is that society is also very hostile to men and boys right now, demonstrated by them becoming incels in large numbers.

incel generally isn't used literally to refer to all people who want to have sex but can't, but a male subset of said group who tend to hold really strong beliefs along the lines of "women won't sleep with me because they're bad", "women only like the bad dudes not nice guys like me", etc.