completely untrue factoid that constantly gets repeated for some reason, there are 3 vacant units per homeless in Los Angeles for example https://gigafact.org/fact-briefs/are-there-more-vacant-homes...
the ratio is about the same in New York City proper, and if you include the entire country, the ratio skyrockets to >27 vacant units per homeless person https://www.self.inc/info/empty-homes/