Citation or clarification or examples needed. If you started a job in 1990 at 25 years old, you'd only be 50 years old today. I don't think unemployment among 50 year olds is higher today than in 1990. So I guess they got upgraded skill along the way? Which fields are we talking about? Nursing? Law? Architecture? Garbage man? Interior decorator? Computer programmer? Car salesman? Retail worker? Heavy equipment operator?
Unemployment numbers don't show it, because that only includes people looking for work. The missing 50-year-old workers are on disability and don't factor in to labor statistics. The Social Security Disability dole swelled from 5M in 2000 to 9M in 2015, nearly double. And it's fairly certain that these disability recipients skew older than the median age of the working population.
http://www.ssa.gov/oact/STATS/dibStat.html (it was responding spottily for me, but search for the url and use google's cache if you need)
Note an interesting trend that while the rate drops from 80.2% for 45-54 age to 64.5% for 55-64, it's been trending up since 1992 sharply, while other participation rates have seen a modest decline.
This could suggest that people 55-64 are more employable today, but it could also mean they are poorer on average and have to take a job to survive. My money is on the latter.
Aren't they generally more employed and at higher wages than younger people?