When I started my first job out of college in the early 90s, I really thought I'd find a good place to work and stay there my whole career, because that's just kind of what I was brought up thinking, and how people in my family treated their careers. Took me six years years there before I figured out how the real world worked, and I left. In hindsight, I should have left three years earlier.
As time goes by, I've gotten more and more mercenary about my career. I think that with very rare exceptions, there is no loyalty anymore in corporate America, and you can be tapped on the shoulder and shown the door at any time no matter how hard you've worked. I learned that a long time ago, and that my employer really owes me nothing more than a paycheck for my work, nothing more. My employer is not out to further my career (which is why I think 99% of all performance reviews are BS and just paperwork). It's up to ME to look out for myself, nobody else, certainly nobody at work. As a result, I've always taken great pains to keep my skills up to date, which is doubly important in the IT field, where change is rapid and you can be outdated and irrelevant in a heartbeat.
If I could give one piece of advice to people just starting their careers it would be...always look out for yourself. Your company is NOT there to further your career. That's your job. Keep your skills current, network, be aware of where the next opportunity might be, and don't be afraid to jump ship to further yourself. Seems pretty basic, but I'm amazed at how many people I see who just sit back on autopilot and expect their employers to look out for them.