The conditions for survival and prosperity
Horace Dediu charts the longevity of technology companies, and notes toward the close that the longest period in which any hardware company has remained in the spotlight -- Apple's 37 years -- is shorter than the career of any of its employees. In short, if you work for a company that makes computers, your employer will almost certainly fall on hard times long before you contemplate retirement.
I don't doubt it, but I think the point goes farther than that. Since I left graduate school in 1997, I have been more or less steadily employed (with the exception of some hard times following the bursting of the first tech bubble), and yet I've never worked for any company longer than 3.5 years. For the last ten years or so, it's been explicitly in my mind that I want to put down roots and focus on the long term in my job, but still: I have a hard time staying in one place for more than two or three years.
When I look around me, I find that the story is similar for the people I work with. On my current job only a few of my colleagues have been there for more than three years. It is now normal to leave a position -- to jump or be pushed -- after less than five years. It wasn't so long ago that this was rare; I worked with some people at Britannica who had been there for more than 30 years. But today? Not at all the case.
Everything is faster today. Entire product segments rise and fall in a handful of years. Businesses pop up, fight the good fight, and then disappear. As a worker, it means the only constant is change: you're always working on your resume, always getting to know new co-workers, always keeping an eye out for the next bit of disruptive change. It's the modern way; even the best jobs are temporary.
Change is not just inevitable, it's mandatory. That can be exhausting, but it can also be exhilarating.