For me it isn't losing figures, but rather finding figures.
I have found a couple figures over the years when I swear I never had them.
As for breakage, yep get used to it. We are talking 40 year old plastic, especially thin plastic for vehicles, and it won't last much longer. Of course it was never meant to last long to begin with. It'll probably hurt more for the big, expensive stuff (FLAGG, Terrordrome, etc).
For me I have an ever shrinking vintage collection of toys. For two big reasons. One, I have replaced a lot of stuff with reissues over the years which gives me more time. And two, I would rather have the money for other things. So while the vintage stuff is still viable as items to sell I am selling. Breakage will make the ones that are complete even more valuable, but even with great care the chance your's (mine) will break is greater. So I don't want to decide to sell one day and find out the item is damaged.