Collateral Lesson: Peering and Sale of Transit are Complementary, not Mutually Exclusive
There exist a set of related fallacious beliefs which cause innumerate people in this industry to lose money:
that it is not advantageous to peer with one’s customers,
that refusing to peer with another ISP can do them disproportionately more harm than it does one’s self,
and most ridiculously, that if you refuse someone peering, they might become your customer instead.