I work with guys well into their 60s who have dual retirement incomes and definitely don't "need" to work but certainly continue to do so. I am sure there are others who have taken it in the shorts from the airlines via furloughs and bankruptcies.... goodbye retirement, who have to continue to work!! I imagine if I were 59 or 64 and was in good shape, willing, able and fully capable to do the job, I would certainly hate to think that I had to go just because I was told that I'm too old.
Meanwhile there's the 35 or 40 yr old guy so out of shape that he probably couldn't fit through the cockpit escape window in an emergency or has just as high of a chance of dieing of a heart attack at the yoke.... or probably a higher chance of choking to death on a burger mid flight.
Fact is that some people actuallly enjoy flying and would continue to do it till the day they die... of old age and I personally think that is a tribute to how great our profession is. I've seen plenty of doctors practicing medicine into their 90's and no one seems to have a problem with that. After all plenty of pilots have died while in flight and the co pilot or captain was able to land the aircraft without incident.
for the record I am 44 and I hate to think of others not retiring holding up progression of my career but I also realize I will be that guy one day as well.