What are your "dumbest" TTRPG costs

[Longspeak]

minimum wage for 1987 ($6/hr)

$6 an hour in 1987?!?!?!?!?!?! I want to go back in time and move to where you were!!

Buying stuff that I have no plan to use in the near future.

Minis and other physical items. Since I've been running games exclusively online now for over four years,

dice

I forgot about dice.

Kickstarters

All of these. I've run almost exclusively online since 1998! Why do I keep buying dice?!?! Or cards?? Or more recently physical books?!?

Roll20.

Here I may disagree. Not about the stuff you said about Roll20, but, having gotten to a good place with it, I am very reluctant to move to a new platform, and nearly certain I'd love at least half my players. And I need my players. I feed of their life force to stay young.

Discord for voice (and dice rolls)

Die rolls?

the very first book I bought that wasn't a core rulebook, and it therefore opened a floodgate

Not quite the same since I was a huge forgotten realms geek during 1e, but nearly the same! Bought the complete Fighters book and it was downhill from there...

Mummy the Resurrection

Read it.

To this I will add.... Buying books you've bought before because a) you sold them and decided you wanted them back, b) lost them, c) wanted one thing from an auction lot, or d) just frickin' forgot you already own it!

The first I regret most. The third reveals the depth of my addiction. The last is just embarrassing. I've done it about four times over the years, but thank god bundleofholding and drivethru warns you or it'd be ten times.

And Patreon. I subscribe to a few and don't regret the ones I use... but what about the ones I don't use? Grr...