I have a hard time believing the disappearing of the mega fauna is solely due to homo sapiens: if it was the case there should be a few pockets of them remainin

I have a hard time believing the disappearing of the mega fauna is solely due to homo sapiens: if it was the case there should be a few pockets of them remaining in the world. For example in western Europe bears were hunted to extinction before the middle ages, but you can still find bears in Russia and in the US.