To be fair like 8 years ago (yes this is sadly true, no idea how I even got schoolwork done at home) my old farts were still on dsl that was one step above dial up internet. Web pages and games froze up all the time.
And, a lot of chain stores that sell monster fish like these don't bother to train their employees right and press the ones that are knowledgeable very hard to meet quotas or get fired. So they give out wrong information or don't stand up to customers just to make a sale. Just go to almost any petsmart or petco and you will see. I stopped in at the local walmart to get soap too, looked at the poorly maintained fish section, as an example it said right on the labels that black pacus and common plecos only get 6" long and green spot puffers only need 10 gallons in freshwater. I don't want to remember the bettas...... Never went back and flatout stopped shopping at walmart haha. People see the reputable brand name and assume the employees and management are right. I think that is probably one of the biggest issues, "but petco said it's fine!!!!". They need to really update their care info. Maybe the media needs to step up and pressure them into changing their ways with negative stories?
Plus the big myths about fish that seem so popular in our culture like "fish can't feel pain and are dumb", "they only grow to fit the tank", "bettas live in mud puddles and only need half a gallon of water" carnival goldfish prizes, and fishbowls still being sold and perpetuated in as seen on tv stuff, movies, ads and other junk really doesn't help.
Perhaps case with the op was just not really having access to new info or settling back into old outdated ways since nothing else went wrong or he thought the myths were right? I wouldn't be surprised. Lotta bad stuff out there for the first time fish owner.