And to add, the flavor of the week cycles too. Tri-5 Chevys, especially ragtops spiked, then dropped.I remember watching an interview with Jay Leno a few years ago and he pretty much said exactly that. You can never know which car or marque might become valuable in the future, so you may as well buy what you like, and enjoy it.
Earlier days, Mopars were the bottom of the barrel. Then, boom! They demanded peak prices.
As of late it's 50's pickups. What's hot next? It's anyone's guess.
Like I say, buy what you like, enjoy it. Life's too short.