What a wonderful industry we work in.
What I'm saying is that if you're a professional and you're not keeping current, then your lack of currency, more than your age, will hinder your employment.
That being said, there are age biases out there. Young managers can be intimidated by hiring an older person, especially if they are insecure. And like the antecendent of this post older people who have 'been around' can sometimes see the reality of things which are uncomfortable for others to admit are true.
The extra time, 10 - 15 hours a week, keeps you current. Would you want to visit a doctor that only put in 40 hours a week seeing patients, and never studies recent medical advances? Or a lawyer whose case law knowledge did not extend beyond their own experience?
If you work in tech and honestly expect to only put in 40 hour weeks for your profession, as you get older you will end up in a dreary IT department -- not a software company -- and eventually be laid off.
BTW Chuck I remember NIS+!
Everyone needs to stay current. And people who do stuff in their own time often have no trouble finding work because the "off time" work often is more relevant in the next job than their 10 years of experience on their employers proprietary system.
The warning sign should be if all you do when you get home from work is watch tv or play video games, you are falling behind the skill sets of those entering the market.