I've seen this "change your friends" thing before, when it is perceived that they are holding you back. Is it me, or does this not seem a little callous?
I've worked hard to get where I am now, and I've got a good s/w dev job, and am working towards having my own s/w company etc. And it takes a long time and it's hard but I still do it because I've a clear vision of where I want to be. But my friends aren't like that. Mostly they have jobs that they do only for the money, and aren't driven to put the extra effort in outside of work in order to get where they would prefer to be.
I have quite a few friends (I like to think!), and I'm not friends with them because they further my own selfish ends, I'm friends with them because they're good people to be around, they're funny and witty, and we're pretty much guaranteed a good laugh when we get together. I couldn't imagine deliberately splitting away from them in order to meet more business-minded people.
Surely if you "choose" friends (because making good friends is really as easy as saying, "I'll have you, you, and you") solely for selfish means then you're not being a good friend to anyone. Although I do want to make money and be rich and run my own company, I have no interest in being the next Tim Ferris (author of The 4 Hour Work Week), who I see as being the personification of self-interest.
This is not meant as a criticism, only that I think that we should be careful with the "change your friends" advice. Good friends are as much an investment of your time and energy as anything else.