Job security, 401k, health care benefits, etc. Same reasons anyone signs up as a permanent employee anywhere.

I'm almost 38 and had my first child not too long ago. Sometimes I surprise myself at feeling tempted to chase the illusion of "stability" at a bigger company. Then I remind myself of all my friends who have been through terrible layoffs and remember that there almost never is such a thing as stability nowadays.

I think a lot of people get the same feeling I do for the same reasons, but then forget the whole "remind yourself" part.

Some companies actually do have career paths of technical people, and most companies will claim to have them. It's hard to tell from bottom rung exactly what track you may or may not have a few steps up.

This isn't always evident from the outside, and it may not even be evident from the inside, until you realize you should be advancing along that non-existent career path.

Most companies do have technical career path. Being a permanent employee not only gives you the benefits (others have listed them), but also lets you work on much more interesting projects (contractors typically work on isolated projects rather than on core systems and algorithms; I know, of course, of exceptions to that but they're rare). It also frees you up of the overhead of finding the next contract.

I know many people who have done contracting and several told me a) the money _is_ very good b) other than the money, it's not worth it (stressful, uninteresting projects, high overhead).