according to the crooks, why does a person need a companion?

According to Crooks, a man needs a companion, or he'll get sick.

A guy needs somebody- to be near him." He whined, "A guy goes nuts if he ain't got nobody. Don't make no difference who the guy is, long's he's with you. I tell ya," he cried, "I tell ya a guy gets too lonely an' he gets sick."