Actually... they are.
I have thousands of comics. Only a handful are worth $100+ with the rest firmly in the $.25-$.50 range. That includes dozens of Superman and Batman titles from the early 60s, most of which are worth their original cover price which means I lost money due to inflation. The only ones I'd purchased back then that are worth anything are the first few Gold Key Star Trek comics. Like my DVD/BR collection I do not purchase with an eye towards them being an "investment." I simply purchase what I like to read.
If you don't believe that then you need to talk to those misguided people in the 90s who got into comics as an "investment." Most lost their shirt buying alternate covers, "limited" edition titles, and the flavor of the month superhero books. Hardly a week goes by at the LCS where someone brings in a long box (holds ~300) of comics expecting to get rich only to discover it's worth less than $100 - if they drive 70 miles to a city where there's a store that will buy them.
I have a few thousand "Magic The Gathering" cards from the early days of the game. Most are worth a few cents with a few going as high as a few $$ (maybe more - I've never bothered to check). I purchased them to play and not as an investment.
I had baseball cards as a kid. I purchased those to put in the spokes of my bike to make it sound "cool." I chewed the gum (horrible stuff in those packages).
I have some WWII foreign coins a great uncle gave me decades ago. The last time I bothered to check they were worth face value.
I have a few Canadian dimes. They're worth ~$.075 each.
Anything "collectible" is only worth what someone else is willing to pay. What it is doesn't matter. Just watch a few episodes of "Pawn Stars" or "American Pickers" for proof.
