Part of the reason homelessness exists is to economically say "you can't afford to live here." Why do all these homeless people aggregate to large cities propor

Part of the reason homelessness exists is to economically say "you can't afford to live here." Why do all these homeless people aggregate to large cities proportionally higher than in the midwest let's say? Cause nobody aspires to get famous and rich there. But homelessness is marginal in most areas because housing is hardly an issue.