The Collector
I've never been much of a collector -- too much organization and money required -- but I am a bit of an accumulator, especially when it comes to drum stuff. I have a couple of bass drum pedals that are older than I am, I've run out of fingers and toes to keep track of snare drums, and let's not get into the cymbal situation. For the most part, I'm able to admire collectibles from a safe distance, but that doesn't mean you have to. There are a lot of good reasons to collect drum stuff.
Buy Low, Sell High
When I started acquiring vintage cymbals, I rationalized that could keep them for a couple of years and then sell them at a modest mark-up. I figured it wouldn't take much for such an investment to outperform the stock market. It's also a pretty popular sport these days. I met one seller who would buy complete sets on the cheap then sell the cymbals, snares and drums separately, and it paid his university tuition!
Value-added Hobby
Whenever I pick up something on the used market, I usually strip it down and try to return it to top condition. It's labour intensive and messy, and it takes some knowledge and skill. But it really doesn't take all that much to salvage a sad-sack item and turn it into something desirable (and sell-able).
Strolling Through History I like to do research, and I can tell you a little bit about each of the drums in my “collection”. Aside from the details of the drums, I've learned a lot about history, culture, tradition ... even economics and interpersonal relationships. It's also broadened my understanding and appreciation of the history and culture behind drums.
Bragging RightsI used to have 1967 Fender Esquire guitar just like Bruce Springsteen’s (which I sold at a 930% profit!) I hated the thing, but whenever I mentioned it in conversation, people were always very impressed. Yes, it's cool to have cool stuff. 'Nuff said.
Buyer Beware
One thing I might caution you about as a potential buyer or seller is a trend to dismantle potentially valuable drums and then sell the parts separately. Yes the seller can make a bit more money, but the buyer has invariably over-paid for the parts, and a possibly wonderful instrument no longer exists. Pity. There is also a pretty good black market in counterfeit vintage drums, so be careful who you buy from. Do your research.
I guess the only other caution would be to point out that, unlike cymbals, drums take up a lot of space. But what the heck, storage lockers are cheap.