Well, as I look at it, there are more Commodore & Amiga computers out there than people who actually want to own one. The reason they seem so rare is that not all those computers have been matched up with people desirous of them yet. There are probably several thousand Amiga users out there, but probably tens of thousands (maybe hundreds of thousands) of surviving Amigas still stashed in closets, garages and warehouses (like Petro's recent find of 500 A1200's new in box). Commodore 64s are even worse!
So, even if you try not to be a hoarder, you can end up with multiple machines unintentionally.
Somehow I ended up with seven VIC-20s, seven Intellivisions, two A500s, two A2000s, five Atari 2600s, several ColecoVisions, etc. etc. etc. not because I was actively collecting, but because people knew I liked the stuff and just wanted to get rid of it themselves.
Also, in the early days (like the mid 1990s) people really wanted to get rid of this "junk" as it was seen as totally obsolete and hadn't developed any retro "chic" yet. How could I resist going into my local thrift store and seeing several nice clean Intellivision consoles for $2.99 each. I just had to pick up one.
Being in my late 20s and early 30s in the 1990s and early 2000s, I finally had the income to buy all the consoles and retro computers I could never have owned in my childhood, and all for dirt cheap as nobody wanted them....I could buy handfuls of cartridges for only ten bucks....so I might have been a little enthusiastic.
Now that a few years have gone by, I'm mellowing out on the retro stuff and starting to pare down. I've sold some nice Amigas to other interested parties, sold off a few Vectrexes, etc. etc. and plan to sell off more of the stuff I never use. I'll only really focus on the main systems I enjoy, like VIC-20 and Amiga, and not even actively collect more for them....sure if I stumble across something unintentionally I might buy it, but I won't actively hunt for stuff.
Emulation has also gotten a LOT better - they even emulate the television blur, floppy drive sounds, etc, etc. Sure it's not the same as a real, physical device, but for those systems not in my main field of interest - like the C64 - it's great to fire up an emulator and play a quick game once in a while than have a whole system set up all the time.
I'll probably keep one of each system I really like...and maybe a few backup parts. But it's time to pare down to a useable level (but still not throw out the baby with the bathwater).