Are you capable of answering the question as to why someone would want a vintage computer or just ad hominem attacks? Because if it's only the latter, that would assure quite the disappointing discourse wouldn't it?
He may not be capable of answering it, but I can. Nostalgia is the biggest reason for sure. While there might be emulators for the C64, Amigas, Atari 2600, and others, it isn't the same. Not even close. Also, by the time the more powerful Amigas were being introduced starting in 1990 (the 3000, for example), I was a poor college kid and couldn't afford one. It is pretty cool being able to restore one and expand it with stuff I could never have afforded back then.
Secondly, people aren't running Commodore 64s in place of modern systems. I have a Vic 20, C64, C128, Amiga 2000, and Amiga 3000. I run them occasionally because it is fun and brings back epic memories but my PC is my main system. Not sure how old you are, but if you're my age (44) or close, you'll recognize the late 70s-late 80s as the golden age of computers and the 90s-early 2000s were, IMO, the golden age of PC (PC clones) gaming.
They wrote a TON of software (mostly games) for the C-64 and considering it's an 8-bit machine operating at 1Mhz the programmers had to write efficient code for it and they generally did. The issue today would be display as I don't think it would hook up to today's TV's.
Actually, it does. I built a cable and connected my C128 (and C64) to one of my Panasonic 1080P plasmas that has an svideo jack. Works great! The monitor out ports from the old Commodores are just svideo signals with a different pinout. The Vic 20 is different and I haven't gotten that to work, but I only spent about 10 minutes trying.
