I'm 61, writing code, and having fun. My advice:

First, find a company that lets you do what you want. In particular, find one that doesn't push you into management (unless that's what you really want). Many companies will push you in that direction, but unless you're really good at it, it's a dead end.

Second, don't get stuck on the same project forever. Being the old fogey who knows everything about that important legacy system isn't a good place to be when the old system is finally retired. It isn't enough to "keep up with new technology". Knowing it and doing at are different things and are judged differently.

Third, don't expect that your superior wisdom is enough. Be wise, but be productive, and help other people be productive.

Not to defend Amazon, you have misstated the situation. They books he bought are still on his Kindle and still readable. He can't buy any new ones, and his subscriptions are canceled -- meaning he doesn't pay for them, and he doesn't receive them. The stuff he *bought* is all still there.