No doubt personal and business too. How can it not be a strong personal element for Michael? After Mac broke his jaw, and Sollozzo, bodyguarded by Mac, keeps trying to kill his father
True Vito didn't know it was Michael who had killed Sol and Mac
until he returned home from the hospital
True Sonny and Tom didn't ask Michael to kill So and Mac-- Michael
volunteered to kill them--he
wanted to kill them, to save
his father's life. The novel also tells us He really had to go, his bowels were loose
I too reckon, there was no other [viable] scenario” they can't wait, because Sollozzo was going to kill Vito ("That's the key for him.")
Second: Donship
Sure thing Michael could have refused the Donship Then again, Michael's loving father and family man Vito never should have put - never wanted this for you son - who “saved [Vito's] life. And paid a heavy price:” in that position
Vito “chooses [Michael] to become the Don, setting in motion Tessio’s betrayal, the Great Massacre of 1955”
carried out as per Vito's counselled strategy
after his death and renouncing Satan -- after the Baptism massacre, he was living a "legitimate" life and public Benefactor
The "machinegun attack" was Roth not the rackets
