Rarity value. Mass produced items are unlikely to ever be collectible until long in the future when most have been destroyed by time and indifference.

Vintage Cars and planes. They don't make 'em any more. You can make a copy, but it's not authentic. The trick is to sve one from rust and misuse for long enough for the others of its era to pass on. Than you have an investment, rather than a junkyard.

Land - thay ain't making it any more (was that Lincoln?). Not quite true geologically speaking, but as good as from most human perspectives. (Reclaimed land is Expensive with a big E).

"Collectibles" - make money for the manufacturer, mostly.

COmic Books - yes, but there were millions printed so you have to go back to a time when nobody cared. If lots of little boys (and girls) stored a heap under their bed, they won't be rare. Mint condition copies will be rare - so go for quality and PRESERVE IT. The sorry thing is, if you own a valuable comic book, you can't read it or you'll devalue it!

(Like vintage wine - you can't drink it, and it probably tastes like bathwater, but if there are only 3 bottles left in the world, someone will pay to have it on their shelf. One day, some fool will open it and be sadly disappointed...)

In most cases, time leads to rarity. The skill is to invest in areas where time ticks faster for one reason or another.

if I knew the secret of that, I wouldn't be so rash as to tell everyone, unless I wanted to hype something - watch out for that! The insiders often take a position, hype the stock (or whatever) and then sell as everyone else buys. They can point to a track record of 400% gains and you say "How does he do it? I followed his advice and only made 20%? Or even lost out!.