Anyone over fifty can hang it up. I'm lucky to have gotten within shouting distance of retirement before finding out that age discrimination is the deadliest force at work in unemployment.
I know where you're coming from. I wake up each morning and thank God I have my living made. I'm coasting to early retirement and do not have to subject myself to the discrimination which you most accurately describe. (Knock on wood)!
Not so long ago, age meant maturity, knowledge and most of all, experience. It was prized.
Now, the situation with respect to age is something of a reflection of the throw-away society we live in. Buy something, use it for a while, get what you want out of it, then toss it and get a newer one. It's the same for workers.
As is obvious from some of the comments on this thread, people are simply commodities. Mere pawns in a game.