My take, for what it is worth!

Vito was instrumental, contributed and caused, among others -

Sonny's death
Sonny died trying to protect his sister from the abuse by her husband because Vito did nothing

Fredo's betrayal
Vito “stepped” over Fredo making Michael the Don but did nothing for Fredo not to foster jealousy, resentment of his kid brother

Michael's misery

• Vito planned all the dirty work - killing of Carlo Rizzi [for Michael to make his daughter a widow] and Moe Greene, the baptism murders - for Michael to carry out after Vito's death thus leaving a murderous legacy for “I never wanted this for you” son
• Vito “knew that he could never be “legitimate” in their world, but he hoped for that in Michael: Senator Corleone, Governor Corleone…” thus placing the impossible, unrealistic burden - and Vito's “goal” for Michael - of the “obsession” on Michael “the source of his lifelong frustration:”

Connie's insolence, whoring, neglect of her children because of her widowhood

Thanks! Pop indeed