GPL, BSD, Opensource/Free Software movement.

I've be a mindless supporter of these movements for years now not because I was a developer myself but because most of them provided me with a lot of useful free software.

However now that I'm becoming more of a programmer I'm questioning the ideology behind these movements.

1. For which situations are these intended? For every developer?
2. Doesn't it go against the developer himself? How can he secure profit while still sustain such projects?

Just willing to learn.
Thanks.

Can anyone give me some insight on this?

I know companies like RedHat exist but is this whole thing going to work for the rest of the software companies?

I know that GPL and BSD don't say anything on pricing of software but if you are forced to provide the source code, aren't you basically giving your work away for free?