A colleague at the time of the 2008 crisis was unable to retire. His stock portfolio (he was overinvested and did not balance his risk properly, especially considering his age) dropped from near a million to about $100k practically overnight. He owned his house (good), but the capital that would've carried him easily to the point where he could use his 401k and later receive social security was gone. He had to work several more years than planned. People don't consider risks very well.
I was working at an Ivy and had coworkers (all professional staff, finance adjacent - theoretically above average preparedness) shift their investments into bonds, locking in losses at close to the bottom of the market. It hurt hearing people talk about that and knowing that it was too late to recover anything.
