Professional athletes have a hard time turning off their competitive drive. That’s why we get things like Jim Harbaugh having a pushup contest with a walrus or Russell Wilson playing one-on-one with a sea lion.
Not that these are bad things, of course.
But it must be pretty damn difficult for Las Vegas to set a reasonable line in inter-species events. Plus, people are cleaning up on the “will it be adorable” prop bet. Always a lock.