Idk, some evidence is quite compelling, but you still don't want to believe it.
e.g. for the Oklahoma Bombing, there is the local commercial TV news footage (in the immediate aftermath) which talks about unexploded bombs found inside the partially-damaged building. Which is pretty weird TV footage to even exist, seeing as officially they deny there were any such bombs, yet we have mainstream local TV footage of them saying that there were. ATF is pretty dodgy in my opinion, they turned up in all sorts of scandals around the same time, 1992+, Waco and Ruby Ridge etc. That was their own building that got blown up, but amazingly they were the only people in the building who didn't go to work that day. Every other organization which had space in that building suffered casualties. And wtf were other bombs doing in there? The bombing switched the media coverage from "ATF are assholes" to "ATF are heroes" and netted the local ATF about $25 million in additional funding. Profit.
Another 1990's example is the Judy Bari bombing. You have an Earth First anti-logging activist, and a pipe bomb goes off in her car, and minutes later a newly-created FBI counter-terrorism task force descends on the scene and arrests her as a terrorist transporting a bomb (for some reason she stuck a motion-sensitive pipe bomb under her ass - it put her in a wheelchair for life). Later, it turns out every single agent there was trained at "bomb school" by the lead agent 1 month prior, and they practiced planting pipe bombs in cars and responding to the incident. Bomb school was held on land belonging to the logging company that was the target of the protests. BTW, the same logging company was also spreading forged Earth First literature which contained violent threats, but they had elementary mistakes such as signing the name of the leader of Earth First "Daryl Cheney" when his name actually has 2 r's. A guy is unlikely to both mistype and mis-sign his own name.