Because it's trivial to take an existing healthy business and extract value from it? Literally cannibalizing a business is a way to make money. The group that killed Sears for example knew what they were doing, and got very wealthy doing it.
As long as there is a nonzero switching cost for any business relationship, it is profitable to take over that business and milk that switching cost for pure profit. Switching costs go up non-linearly as your market approaches monopoly or duopoly.
As long as there is a nonzero switching cost for any business relationship, it is profitable to take over that business and milk that switching cost for pure profit. Switching costs go up non-linearly as your market approaches monopoly or duopoly.