''I should have'' is a similar burden. ''Should'' implies some authority or information source was/is available on which to base a previous decision. But the plain fact is, no one knows exactly what will happen with businesses and jobs and markets. You couldn’t know in the past, and you don’t know right now.
This is distressing. When I was young (ouch! so long ago), the expectation for most high school and college graduates was to get a job, have it for 30 years, and retire. Many people from my father’s generation did just that (after WWII). Many people from my generation expected it. Some achieved it. Today, however, that is very unusual, and it is an unrealistic expectation for a career. It used to be that in a recession, people would be laid off for a while and then return to the same job. In recent recessions, however, whole companies close, industries relocate, and the jobs no longer exist.
There is no good choice that leads to stability in a job itself. The sort of economy that allowed for such stability no longer exists. Today, much more is required of the blue-collar wage earner. What do you need to do now, while you have this job, to prepare for the next (hopefully better) one? There will have to be a next one — almost everyone changes jobs within five years. This is true whether the economy is in recession, boom, stagnation, stagflation, credit bubble, or burst bubble. So don't wait.
Get started now. Are your employment records and references up to date? Most employers want a resume to generate interest, then want that followed with a detailed application. Are you ready to apply somewhere else? Do you pay some attention to want ads, job boards, word-of-mouth? Do you have contact with other co-workers after they leave? The best job lead is from an insider. You may not take another possible job, but it is a great boost in self-confidence for you to know you could. Are you getting all of the employer-sponsored training you possibly can? Are you checking out appropriate training or education on your own? Or are you just hanging on, hoping the axe doesn’t fall?
If you do stay prepared, you can maintain and advance in your present job, or locate and secure a better job. Then, even if the axe does fall, you are already doing the kinds of things to locate a new employment situation while unemployed. If you are now unemployed, do all your job-hunting routines and then stay active while you have the next job.