Depending on species, monitors will actively hunt you for sport ?
I had an Argus that my ex made me get rid of. She said it seemed like it was always sizing her up. She let her self out of the enclosure a few times. She learned she could unscrew the vent covers and squeeze out the hole. She was about 4' long. We had her from a baby. I never saw the menace that the ex saw maybe the Argus could tell my ex was ex material before I saw it. Shoulda kept the lizard.
We also had a black rough neck that was really chill but its claws would tear you up whether or not it was trying. I saw the intelligence in their eyes and actions. If you haven't experienced it watch Jurassic Park any sceen involving the raptors. You can watch them problem solve I can see why people would be unnerved by it, but to me it's just fascinating.
The nile, croc, water monitors just get to big to safely interact with even if they aren't thinking of eating you. Let alone food bill and housing.