I have never really experienced any kind of "job security".
The reality is that no job has 100% security even if you're self-employed. Naturally, some sectors will always be "more secure" than other sectors depending on what the economic trends are.
Mine comes pretty close - working at a nursing home. Definitely a "job is yours to keep if you want to" thing due to the high turnover and burnout. Only reason I myself haven't yet been a part of that high turnover is because I live about a hundred feet away from my job - and I REALLY hate commuting.
Really nasty (and sometimes downright shocking) job, but I'm glad to have it on my resume. Very solid "backup option" for employment.