I had a similar thought just recently to start collecting Pokemon cards again. I looked up the prices of first-generation Pokemon cards and I wish I kept the cards I had as a child because they would be worth a fortune right now if they were in good condition and in my possession.

Have you seen the price of a first edition Charizard on eBay? It's absolutely insane to think if I had my first edition Charizards, I would be able to fetch an absolute dime for them: https://www.ebay.com/sch/first%20edition%20charizard%20card

These days I find myself collecting old games (game cartridges) and have built myself a sizeable Wii-U collection of games knowing it's going to be a cult-like console in a few years time with people clamouring for games like we see with the Dreamcast.