This is a strategy question without a one-paragraph answer and a bit out of the scope of this post.
I've lived in close proximity to many unhoused people for years, not everyone that can't afford to join the ridiculous housing or rental markets is struggling to get food in their mouth. I've known many personally, they're not all starving maniacs like the stereotypes. Some have jobs and cell phones, many have belongings, things they've found, been given, or were gifted. Many are nice and happy to tell you their story in exchange for some respect.
In fact, my perhaps unorthodox opinion is that left should be uniting with this group rather than trying to convince well off liberals to resist vague threats of fascism.