There is one externalizing factor they point to that the left generally acknowledges as real and serious; racism. People think of incels as angry white male losers but many, many are not white and point to it as one of the reasons for their inceldom. They even have their own names like currycels for South Asians and ricecels for East Asians.
The left has even started to consider this a problem though outside the context of the incel conversation and more so in the context of dating apps and social media where some users will blatantly say on their profile that they do not want this or that race contacting them or even specifying "white only". They call it
"sexual racism" and its particularly bad in the gay community.
So I wonder how leftists in general feel about these claims of racism by the incels given that they themselves acknowledge its a problem in other contexts. As a leftist I do think they have a point here but its still not sufficient an excuse on its own. You could always stick to your own community and culture if others are prejudiced against you. And if you're a Pakistani currycel there's always cousin marriage.