Most likely these fake accounts are created by firms who are selling access to mass-likes/follows. They sell the ability to get 10k fake accounts to follow your legitimate account, if you wish to boost your legitimate account, for some reason. Or, these fake accounts are created by intelligence agencies in order to run influence operations. Both of these possibilities have been reported on in the mainstream press. Maybe there's a third explanation that I haven't considered.
Trash sellers looking do dump volume onto Amazon are leveraging tools to generate volume.