It is difficult to forgive someone who is not in the least regretful or repentant. Someone who instead of expressing regret, cheats a second time! And this time for money, as well as ego.
It is because Rossi has only been running for two years, that he does not understand why others just can't let this go. For many of us, running is an obsession, a passion. Many of us have left part of ourselves on the road while attempting to qualify for Boston or to get a podium finish or a personal best. And I don't think Mr. Rossi is mentally ill. He just took a shortcut to gratify his own ego and never expected to get caught. Instead of going silent and letting the media circus die down, he continues to double down. Due to his own ignorance, he doesn't know how ridiculous everything looks.
As long as he wears that Boston gear, I can't see an ounce of regret in him. Not only does he not regret his cheating, he is IN YOUR FACE proud of it.
FWIW, I also subscribe to the theory that he hung around the start and finish of the Turkey Trot to trigger the mats. He did not use a conspirator. The reason for the 20:25 instead of sub 20 and his tweeted uncertainty about the final time is that he could not be sure if he triggered the mat when he walked close to it.. He probably strolled by the finish line mat a few times and wasn't successful the first few times he passed it.