not totally accurate though.
Of course I can't talk about how people become homeless in the US but in Germany is pretty darn hard to. You have to almost actively avoid all help and choose that way of life. Otherwise you apply for Neetbux, get an apartment and enough money for groceries and stuff.
I guess most homeless people have some kind of mental disability that prevents them from being a "normal part of society", maybe just an addiction to drugs. And this disability also makes other people avoid them or maybe they avoid other people as well. Interpersonal security mechanisms can't work that way.
When it comes to the needs of homeless people: of course sex isn't their priority no1. But we know for many years that Maslows's pyramid of needs is not really that
accurate and you can be in need of physical contacts even if you don't feel fully secure and nourished 100% of the time.
In my experience "normies" (e.g. people who have or have had sex and physical attention on a regular basis) can't deal with not having sex for longer periods of time like people with no sexual experience do for obvious reasons.
I'd agree that most people who identify as "incels" are the way you describe them. If you take the word's literal meaning though and include other sorts of permavirgins, there are a lot more reasons.
Just visit r9k and look at the occasional "I just want to cuddle" threads. Many of them just look for a companion, someone to love and to be loved by. And although they don't look for sex above else, they can't get what they long for because of various reasons, be it anxiety, strange personalities or, in some rare cases, looks.