I'm a younger guy, and I'm still building my collection, but I've been on the other side of the coin enough times that I have some thoughts.
Age doesn't have as much to do with it as ability and use, IMO. I don't care if you're 95. If you're in the shop everyday, then yeah, keep the tools. If its been years since you've even touched a machine, sell it.
My dad is a hoarder. Not like, newspapers and garbage, but just stuff. Pops lost his job somewhere right around the housing crash in 08, and we had to sell the farm. We had a HUGE auction. Took 2 auctioneers all day to sell all of the lots. And that was just the stuff he decided he could part with.
Today he lives with his wife in a tiny cottage on a lake, but his garage is overflowing, he has a carport full, and 2 storage units. I can't get him to clean out the storage units at the very least. Costs him like $200 a month to keep stuff he doesn't use. I've offered to help him craigslist, ebay, garage sale, whatever. He agrees its a bad thing, but still won't do anything about it.
It runs in our family. His uncle is in his 80s and has a very nice shop with a lot of nice tools, machines and collectibles. When he dies, its going to be a **** show. People are going to come out of the woodwork and the vultures are going to start dive bombing. I would like to buy some stuff from him before he passes on because I know its not going to go well when the day comes and he's not there to make the deal. I pity his daughters and the stress this will cause them.
My point is, take care of it now. Start today. It piles up and becomes a huge hurdle.
I have bad genetics with this. I know the struggle. I have a REALLY hard time trashing anything of conceivable value. I just hate throwing away good things. Donating or selling helps. When I moved shops last, I had to toss some really nice stuff that I simply did not have room for. It was freeing and hurtful at the same time.
My rules are as follows.
It must be used at least once a year to live in the shop. I simply don't have room for stuff that gets used more infrequently than that. The exception is specialty hand and small power tools, as they just go in the box and I have plenty of drawer spaces. I pay X dollars a month for X sq. feet. Each square foot has a monthly cost. If it doesn't earn its keep, she gots to go.
No new projects that are not profitable customer work. I have a few irons in the fire that are enough of a pain. No more. I will just pay the money to buy a new machine or tool. I can't take the time, energy and space to rehab old iron. I love doing it, but the economics just aren't there anymore. If I need one badly enough, the jobs will pay for a good working one. Otherwise, I guess I don't need it.
Two is enough. I pass on tools now if I have two. Some stuff I already have in triplicate. I no longer need 3 full sets of tools. One set for the shop, maybe a set at home of some stuff if needed.
No storage for friends. I have a few friends that pay me to keep stuff with me. They get a pass, because they pay. But I'm not going to store motorcycles, campers and whatever because you chose to live in a subdivision with no land.