*Disclaimer: I went the manager path*
Yes there is ageism in IT. There are types of jobs that you will never get hired for beyond a certain age, as you will be viewed as too expensive for the position. For instance, no one ever hires a 35 yr old for a entry level coding position. As you get higher in age, the fewer avenues are open to you. Eventually you end up with a choice between high level technical specification (Sr Architect positions, etc) or Management.
The problem is that there are very few senior architect positions. Ergo, effectively as you get older, the jobs get harder to get, and you get an effect that is pretty much indistinguishable from discrimination. (I'll stay out of if it ACTUALLY discrimination - that's a hair for legal types to split, not I)
So if you're very good, you can keep on in Tech. Put your ego aside and ask yourself if you're actually that good. Or better yet, ask someone you can trust.
Now for myself, as I came up the ranks of techies, I noticed something. There were very few good IT managers. Good being defined as:
1) having a clue about what they're managing (IT)
2) giving a shit for the people they are managing
3) being able to talk to both the IT guys and the Business guys without getting shot by both
I am arguably good enough that I could have gone Architect. I currently manage a team of them, and for the most part I keep up. I think I better serve the organization where I am though. I keep the shit from hitting my team, provide constructive feedback them in terms of budgets, org politics, and business realities, and try to ensure that the company doesn't make a mistake because IT didn't communicate effectively enough to them in terms they can understand. (Techies: We need a new core switch, we're hitting 8Gbits on the backplane!) (Business: Whats a backwhozit?)
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