OK, so you're growing some weed in your house, and you need to guard it - totally rational! You could get 10 black bears, but shit, you're busy growing and selling all this weed!
Who's going to take care of the bears? Who's going to comb their fur? Feed them? And if someone breaks into your growing den, presumably they've got a gun - do you know how easy it is to shoot a bear? I don't, but I'm guessing pretty easy - and then down goes the bear, and your stash. You know what's smarter? A fucking alligator. Does anyone even know how to kill an alligator? Do you step on it? Strangle it? Too late - your weed-stealing arm just got chomped off.