Women can smell the slightest hint of desperation from a mile and it's their biggest turn off, and incels in general and this manlet in particular reek of it. It's how such men carry themselves. I'd argue that as an ugly man you have better chances than as an ugly woman to find someone if you carry yourself the right way. Contrary to what incels believe (because autists are bad at theory-of-mind stuff) men are a lot more looks-oriented than women are. If you just look normal as a man (be clean, have a somewhat normal face and fashion sense, don't have the circumference of a small moon and the BO and skin diseases to go with it) looks aren't really a thing you have to worry much about when dating. Incels are obsessed with their looks, but it's really their smallest problem. Hell, you can even get away with being slightly fat, which women can't get nearly as easily get away with. Being able to comfortably interact with a woman from a peer position, being confident (without overshooting and being a dick) and being competent at things is incredibly attractive to most women I have met. Looks actually come below that.
If you wanna know why an incel can't find a girlfriend, just listen to him for five minutes. Why would anyone wanna be with a person who thinks and behaves like that?