The facts that the FBI allegedly found "explosives" in the shooter's car, that he had had been a member of a shooting club for the past year and that he had zero internet presence together strongly suggest that he was a developed FBI asset. He was groomed online and radicalized, then likely subjected to physical MK Ultra style brainwashing techniques at some point. His handler encouraged him to practice shooting, both to make him more effective as an actual assassin if needed or simply to make him a more credible patsy. When the decision was made to initiate this operation, Crooks's internet history was scrubbed by the FBI both to hide their involvement and to render him a total cypher whose motives were impossible to discern.
I'm open to the idea of there being a second shooter, but not entirely sold on it. It's certainly possible. It's also possible that Crooks wasn't actually anywhere near the rally - he could have been disappeared by the FBI while they had Maxwell Yearick actually on the roof, who then, in death, assumed Crooks's identity (which was scrubbed and unimpeachable in contrast with Yearick's extensive criminal Antifa activity). The fact that the shooter had explosives in his car with detonators on his body makes utterly no sense, but is exactly the sort of scary-sounding crap the FBI loves to associated its patsies with. And frankly, the idea that this loser 20 year-old (with NO internet history whatsoever, I remind you) would have even been able to construct explosives by himself (in his parents' garage???) is totally unbelievable. And then, assuming that against all odds he somehow did manage to build explosives, why would he just leave them sitting in his car on the momentous day? The only rational explanation is that they were placed there to be found by the FBI to make him a more credible patsy.
What is utterly indisputable at this point, doubly so after hearing the pathetic excuses about the sloped roof from the female Secret Service director, is that this was somehow an inside job. At the very least, the lines of communication between the local PD and the SS agents on scene were deliberately confused to give the shooter cover to infiltrate the rally and scale the building. In addition, one or more persons in a command authority within the SS were likely feeding their agents on the ground deliberate bad information, and probably misleading the SS snipers into thinking that the shooter was a local PD sniper. There is no other way to explain how the shooter was able to remain on the roof for so long after having been spotted and reported to both local PD and the SS.