There are quite a few people who actively aspire to live in vans on the streets of the bay area. There are more who are on the end of having other options (but don't want to, say, have a connivance store job in a small midwest town) but don't take them for whatever reason. If you had a few resources, wouldn't you rather try to make your way to live in SF instead of NY, especially in January?
Being young makes it more likely that the lifestyle is a choice and when it isn't, being young makes it easier to migrate to the best possible place to be homeless.