Is there anything you were once taught about horses, that you now know is incorrect? When I first got into horses about a decade ago, here are some of the things I was taught by "experts"
No such thing as "brown" horses, they're either bay or chestnut.
If a paint is not a pinto, it isn't a real paint.
Cremellos or perlinos are albinos and cannot be ridden due to brittle bones!
To ride a horse, you kick to go fast and haul on the reins to stop. You don't need to know anything else.
And my absolute favourite - you don't need to worm or vaccinate your horse if it lives alone because it can't catch anything...