These memes about Kaidou don’t make any sense — once again, they only make sense if there’s ambiguity and if they’re interpreted the wrong way.
If Kaidou only had a Devil Fruit, fine — but the guy also has insane Haki on top of that.
The fact that he has a Devil Fruit doesn’t cancel out his ability to train and have strong Haki — which, according to him, surpasses everything.
The fact that Kaidou possibly hasn’t awakened his Devil Fruit should already mean he’s not a DF merchant, since he hasn’t fully exploited it like those who awaken do. Kaidou is just insane — he has a Devil Fruit that’s already considered one of the strongest in existence, and he simply adopted the mindset that Haki surpasses everything, training and maxing out his Haki. The guy basically beat the game twice.