Oh man, rules change so fast. Ill have to remember the next time so I dont make everyone stupider.
from Mirriam-Webster
"Stupider and stupidest are real words in good standing. While there are many (often contradictory) rules on comparative and superlative adjectives, there is no rule against stupider and stupidest, and the words have a long history of usage. "
https://www.merriam-webster.com/words-at-play/are-stupider-and-stupidest-real-words
Discussion
I honestly don't recall them not being words and I'm going on 47. Although I do vaguely recall having an anal retentive english teacher in 4th grade that was opposed to their use. My guess is its a common vs proper grammar thing