As has been mentioned, there's no such thing as too old for this hobby!
That said, it may never seem like it to most of us, but there's going to come a day when we're not going to be around anymore, and that our chips and other collectibles will be passed down to the next in line or sold.
Me? I'd rather live to see my son and his friends enjoy some of my sets. I plan on passing down a set (or two or three) to him while I still have my faculties so I can see him enjoy them some before I pass on. There will be sets that I will allow to be sold, but some are going to be vaulted and will never want to see them leave the family.