Has an M1 main battle tank ever been destroyed by a T72?
Dan Rosenthal, U.S. Army Infantry, RSTA (Reconnaissance, Surveillance, Target Acquisition), OIF
Not directly in combat, no. As best I can tell, the closest that a base-model T-72 has come to killing an Abrams was an incident in which an M1A1 took three main gun rounds from an Iraqi T-72 in February 1991. One of the rounds failed to penetrate the turret armor; two of the rounds made partial penetrations on the rear of the turret, causing a fire. The tank was cleared of any radiological contamination (from the DU in the armor) and recommended to be returned to service. It was not destroyed, but is the only documented instance of an M1 being knocked out (crew bailed) from an Iraqi main battle tank of any kind.
Another tank, Bumper B-23, from TF 1-37 of 1st Armored Division, took an unknown KE (non-DU, meaning that it was likely Iraqi) round that did not fully penetrate the rear engine grills, but it was destroyed by an ATGM in the battle and caught fire. The only injury to the crew was a twisted knee suffered when exiting the vehicle.
However, consider that a tank duel's outcome depends heavily on the range and angle of fire. In Iraq, though there were several close-range battles, much of the terrain supported long range fire from M1A1 HAs (or better variants) against unupgraded, export-variant T-72s that lacked effective night vision, thermals, or rangefinders. A T-72 that gets a lucky close range shot to the sides or rear of an M1A1 would still be able to cause a catastrophic penetration (consider that in nearly all cases in which an M1 was penetrated by hostile KE rounds, they were hits to the rear).
It's possible that an upgraded, late-model T-72 variant (at least a T-72B or later, including the T-90 series) would be capable of a frontal penetration. Russia did not export the better technology to Middle Eastern buyers, due to the risk of the tanks being captured by the west. So any export variant tank will be inferior to the Russian equivalent (see, e.g. the T-72M series). At least with the T-72B line, the tank is capable of firing the Svir ATGM, and carries the 2A46-M (or 2A46-M5, for the T-72B2 and later) main gun. And the T-90 incorporates features of the T-80 series, but on the more inexpensive T-72 chassis as a baseline. However it's no longer technically a T-72, so it wouldn't count for the purposes of this exercise.