I think a brief timeline on why Tom is the way that he is, is something like:
-Young Tom is just happy-go-lucky, party hard, immature musician who knows how to write good hooks with easy, yet catchy guitar riffs.
-Tom eventually began to resent the band's immature image and wanted to be treated seriously. I think this began around the time of BCR/Self-titled/endorsing John Kerry/AvA making the best album in 20 years/etc. He had an irrational chip on his shoulder to prove to people he was smart/edgy/artistic and wanted to be treated seriously, but he overcompensated for it and his ego fucked things up with Blink/AvA.
-Tom realized the immature image is part of the band's schtick and embraced it again in the Reunion/Neighborhoods era.
-Tom has fluctuated between immature/mature whenever it benefits him. The TTS debacle proved that, while he wanted to be treated seriously and do big things, he doesn't have the critical thinking or business acumen to succeed when he tries to run a company. He was taken advantage of and lost a bunch of money; he believed the dumbest/most fake UFO videos as being real. But he can also be likeable and funny/immature in his social media posts, interviews, etc.
Then throw in alcoholism, drug abuse, and potential mental illness, and you can see why things have gone the way they have.