Yeah, like Mark says, Tom was the grandiose one. He had a penchant of wanting to do wild, big, audacious things and Mark had to figure out how to do that and make it work. In terms of success in the music industry, Tom and him won the lottery 5 times in one lifetime. After Enema came out and did what it did, Mark had been the lead singer for 5-6 of their singles by this point. Only ATST was Tom's. Was that song a giant ploy by him to write a big hit? ATST seemed so calculated and perfect. I always wonder if that friendly rivalry was there at that point.
Take that, add a prescription drug addiction, every album is consistently popular, business ventures like loserkids and atticus doing super well, mobs of obsessed kids, a wife with newborns who would prefer you had nobody to answer to for your job, waning interest in the "punk" genre, your best friend and bandmate not loving all your ideas, the last time you stepped out of his comfort zone with your career he freaked out, and the paranoia/disillusionment of being a rock star with people judging every thing you do, and I think you get why Tom was difficult/secretive. I always sided with Mark in the sense that Tom took much needed time off and decided to start a new band and that's fucked up when you bitch and moan about touring too much or missing your family. The duality of Delonge.