Why is that a bad thing? In a normal 9-5, you spend 1/3 of your waking time with those people.
I'm a few years out of University, and I've now spent more time with co workers than I did with most of the people I went to university or school with. I don't know what's going on in their lives for the most part, we catch up a few times a year and that's that.
You're probably interested in some of the same things outside of work as many of your colleague, and may have more in common with them than other friends You don't need to consider every co worker a friend, and it's definitely sensible to draw the line between working and personal life, but it seems like a total waste to spend a huge amount of your waking time with people and actively refuse to be friends with any of them.