Sometimes/mostly not sure what constitutes a 'collection', when it's far from stamps or coins or bottles and the like.
I don't tend to look at my accumulated stuff as such but...
Tarantulas, usually keep 50-60 of 'em at any given time. Interesting critters...
Of course I'm a gearhead, so Brit bikes, a few Italian, a couple USA and Swedish, mostly older, a few 'modern'. Various running, rolling and disassembled.
A couple older BMW cars and tons of spares...
Gotta have the obligatory few tractors and a pickup truck or two... Bunch 'o bicycles, modern stuff...
Been trying to keep the guitars and guns down to 'non collection' quantities, only what I will actually play/shoot on a semi regular basis, which still can be a considerable number, lol.
I do make a few exceptions for airguns though...
The list could go on...