Do you think dogs are the potential perfect killing machines ?

Since I was young,I have always thought of dogs being the animal kingdom’s perfect killing machines!
(I am in no way badmouthing dogs,so dog lovers back off)
I know they are very loyal & loving animals but I have seen them engage predators ten fold their size and either scare them off and/or dominate them. e.g. Black Bears,Grizzly Bears,Wolves etc,,etc,,

There is video of an incident in Europe, a 1 ton Brahma bull was loose in the streets wrecking havoc,a neighborhood dog trained in handling cattle jumped a fence,chased it down and clamped its jaws on the bull’s mouth,dropped it and owned it!

My grandfather had 6 hunting dogs all but one were disemboweled by a Razorback because they all refused to back down even though they were being torn apart by the Razorback !
(*they were not protecting my grandfather as he was not in danger)
Do you think it is generics,training,courage,stupidity or a mixture of all ??