Why? You'll spend a huge time of your life working, why is it not worth it to build relationships? You don't have to meet them in your free time to consider them friends.
Building a professional network is important, and some bonding is natural, so I don't mean to discourage them. Though I do prefer seeking most social fulfillment through other means.
I don't live in the US, and almost all of my friends I meet on my free time are not through work, but I do have colleagues who I consider friends and it makes work a lot more enjoyable. That being said, there's only very few of them who I would be likely to keep in touch with if they or I quit.