That cargument about brass-age cars is bogus. The problem with those things is they're barely drivable on today's roads - you certainly couldn't use one as a daily driver. They're not as generally useable as say a 1950's or 1960's car. I suppose the pinball equivalents would be flipperless, which are equally as useless. But there's WAY more "modern" pinball machines around than those old bone shakers.
That said, the prices on EMs have been climbing too - I regular see them $1K and more. Which doesn't seem like much but these are games that were $50-$100 when I started. So the tide is lifting all boats.
I have to agree, OP is doing the usual newbie blowhard thing and posting a bunch of crap like they're the first person to ever think of it, even though if you spent five seconds searching Google, you'd see this is well worn nonsense. It's kind of embarrassing.
I mean, if you want to stick to the usual cargument, he's basically saying "The prices of Ferraris are insane! I think the collector market is going to tank in a few years." Really?