That being said, you have to wonder if the goal of shooting Reagan was not to kill him but to give him a warning. The "lone nut" being the son of a close friend of the elder Bush is suspicious on its face. But if the intent were to kill Reagan, there would have been at least one more assassin, as was the case with JFK and RFK. Hinckley was no professional, less skilled than Lee Harvey Oswald. In any case, GHWB got his chance in 1988, at which point he had convinced enough conservatives that he would be at least tolerable. After the assassination, Reagan moved away from hard-core conservative domestic policies, with David Stockman and James Watt leaving the Administration.
The two unsuccessful attempts on Gerald Ford have not been discussed. Nelson Rockefeller was from a family very closely tied to financial and political power. But as a liberal Republican, he would never have been chosen by his party in 1976 or 1980. I don't know enough about Squeaky Fromme, a Manson family member, or Sara Jane Moore, a left wing activist. I can't tie the two women to the Deep State of the time, or to the Rockefeller interests. But when you ask the question, cui bono, the answer is obvious.
Why did Bush make sure Barbara wrote, what is by all accounts, “a weird letter,” just to give him an alibi down the road?