There is one entire category of TTUN hate that, unless I missed it, hasn't been mentioned yet. Our individual experiences with TTUN fans.
Most of us grew up in Ohio. Many in areas with a large number of Ohio State fans. Being a Buckeye is a bigger part of family than grandma's biscuits and mom's apple pie.
The first experience of TTUN fans for many of us are the kind of jackwagons that choose the rival BECAUSE it's the rival. They WANT to be THAT guy. They choose TTUN because they are contrarian bitchtards whose only contribution to anything is to improve it with their departure. Brady Hoke is exhibit A.
For some of the younger BP members (some of whom are in their 40s by now) the group mentioned above actually overlaps with the second major group of TTUN fans; 1990s bandwagon riders. Many of us that were in the working world for that entire decade, regardless of where it was across North America (I was an applications engineer in the telecom industry for much of that decade, so I was in literally every major city on the continent), ran into a metric butt ton of people who claimed to be TTUN fans, and who seemed to believe that TTUN's ownership of John Cooper somehow reflected on their relationship with us.
Another irksome group of TTUN fans, one that overlaps substantially with both of the above, is the Academic Smack Talk DoucheDonut. These guys seem to think that the accident of geography that landed you at Ohio State makes you somehow intellectually inferior to them. Some of these scUM-bags were among the worst engineers I've ever known; some of them couldn't count to my IQ. My upbringing was such that it truly did not matter how smart I was, going to the state school that was geographically convenient was the best I was ever going to be able to do for myself. Add to that the fact that some of the best engineers I've known were completely self-taught, no formal education at all, and you get a recipe for less than zero respect for academic smack talk. And 80% of it that I've heard has come from TTUN fans. The other 20% is from Notre Dame fans who have never been in South Bend and cultists who flunked out of Ped State, but both of those groups are topics for different threads.
Finally, the group that wraps up all of the other sub-headings of TTUN-fan into a giant, seething vortex of stupid is the sense of entitlement that at once makes them insufferable and also renders them the Dumbest Fan Base In America (DFBIA). They (every one of them that I've met anyway) think that Fielding Yost's many wins, using ringers against teams that they'd just taught to play the game, somehow entitles them to permanent Blue Blood status. They truly believe, until October proves otherwise, that THIS YEAR is the return to glory that they so richly deserve, just for being fans of the Harvard of the Midwest. They believe that cheering for a team that has more wins than any other somehow makes them better... no... supERiOr to other people. While every fan base has those fans who attach too much of their own self esteem to the team's comings and goings (looking at you, Bama man), the appalling lack of self-awareness of TTUN-Man to be so much more arrogant about wins from before his grandfather was born than any other fan is about the win from last Saturday... it is no longer surprising, but it never fails to amaze.
In short: We hate them because they objectively deserve to be hated.
UTQTMFS