I'm just starting out in my career, but I find the prospect of future me being devalued because he's a couple years older terrible, and I don't understand why others seem okay with it. Aging is going a second per second for everyone, isn't it?
As a young developer I watched great old developers, fantastic at their job and with super deep experience let go first.
My advice is make sure you save a lot. And be prepared to either retire early, switch careers, or start your own business/consult once you have over 10 years of experience. Connect with people, keep in touch, and make sure you stay current with new technologies.