besides being immoral and a literal F-U to your consumers, it can bring anti trust cases when you are as big as Apple.
https://en.wikipedia.org/wiki/Vendor_lock-in
But other than that, well, just go celebrate your $2 gain on your APPL stocks despite the fact you were prohibited to call 50% of your friends just so someone couldn't save a few bucks when buying a phone for their teenage kid. Go you!