I'm not sure I understand your question of "why not just 1 crazed?" The fact is it was a coordinated plot. The plot included attempts to kill General Grant, Sec

I'm not sure I understand your question of "why not just 1 crazed?" The fact is it was a coordinated plot. The plot included attempts to kill General Grant, Secretary of State Seward, and Vice President Johnson. Yes, the history of the USA would have been very different if Lincoln hadn't been assassinated. Johnson, who succeeded Lincoln, was a southerner from a poor background who desperately wanted the social approval of the (former) slave owning upper class. He was considerably more lenient than almost anyone else would have been in forgiving them for rebellion and restoring their citizenship rights. He stopped the attempts to redistribute land to the freed slaves, which led to decades of almost-as-bad-as-slavery conditions for blacks forced into sharecropping. Personally, I suspect if Lincoln hadn't been assassinated, the USA would have written an entirely new constitution to fix the systemic issues that led to the war, rather than a poor attempt to paper over them with a few amendments.