I definitely feel bad about a lot of friends that I couldn't hang out with any more. That's a tradeoff. Through shared experiences, you learn about people and have people you can really call friends. It can be easily viewed as being exclusive. They go into a rush looking for the people that will bring something into the fraternity or sorority.
Some people just have the wrong impression of the greek system.
We're not an exclusive bunch of snobs, we are not a bunch of lazy drunks. What we are, however, are a group of people that provide sevice to our community, raise money for charities, promote good grades and good attitudes. The greek system is for those who want to get involved, but are already involved some way on campus. Who wants to go to a party and have some fuck from the wrong side of the row lurking on your woman. The selection process is not always perfect, but the right fraternities and sororities on campus usually have a pretty pure strain of people.