Having my cake and eating it too

I just got back from a 40 year anniversary celebration. Not a couple - an anniversary with the company. It got me thinking, what are the benefits to working for one company for basically your entire career? What compels people to work for one company rather than move from job to job? What does it say about the person if they are willing to do that? What does it say about the company if they are able to retain someone that long? Are the days of people working for a company for that long dwindling?
I stood there in the shop area of the building I work, surrounded by around 30 people huddling around a table with a cake, punch, and a present. I knew all but maybe 1-2 of them. A few I had known for the duration of my tenure at L&P (15 years), most I have known for at least 3-5. There were of course a few stragglers who happen to know the guy 'right now' and they were out to have their cake and punch too - no shame in that. It's pretty good cake, and the punch wasn't bad.
Having just had my 15 year anniversary, my curiosity was peaked. What would I get if I hang out for another 25 years?? At 15 years I got a $50 gift certificate in a card during a department 'get together' celebrating not only mine, but a few others anniversaries and b-days. So, for 40 years you get an engraved crystal? I didn't see any cash - hopefully there was some, but I didn't see it. For 40 years I'd be trying for a couple months off?!?! Why not - after that long don't you deserve it? Man, I'd say.
Anyway, I don't think I want to hang around to find out any other uber-cool things that come with the big 4-0 trophy - at least at this fine establishment!!

So, seriously - back to some of the original thoughts - why do people stay? Security?? Fear?? Or, in some really rare cases do they really LOVE what they do?? Do they just have a passion for it?? I think in my case - and I'm only talking 15 years, but that's a freaking buttload - it's mostly that I kept thinking I could change things, make a difference, make things better and I like that. I like to help people to do their jobs better. Then there is also the security of doing something I know and working with people I know and know me. Seriously, some of these people know me better than I know myself sometimes. I do have fear of the unknown and that the grass may indeed NOT be greener on the other side. Maybe I'm a bit of a mid-life crisis person about now, but I just want to make a difference in this world in my own little way. Lately I've realized you don't have to make that difference at work. Also, there are some areas more important to me now that I think I could help make small differences in - childhood obesity, going green, nursing homes, etc...
I'm not at a stopping place in my rambling, but I am in my day, so that's all for now - time to go ride and do more pondering!!