My take, for what it is worth!
From what we saw in the movie, in my view, there is no denying that all the evidence, point to -
“something in it for me -- on my own” was, in my view, the Donship and the only way this could happen is if the current Don, Michael was dead or in prison
However
if Fredo was
not after the Donship and
if Fredo meant no harm to Michael and “Fredo was desperate for approval, he really wanted to be on peoples good side” [not on Michael's?!]
- Why would Fredo throw “I'm your older brother Mike and I was stepped over! It ain't the way I wanted it!” in Michael's face? when “That's the way Pop wanted it”
- Why would the Donship be even an issue? for Fredo
“Let’s be honest Michael initially did give him [Fredo] a pass” Ref: Desert Inn until Fredo's full extent of Fredo's deeper involvement with Roth against his kid brother and treachery were revealed in Fredo's outburst in the boathouse
Nevertheless and in spite of all the mounting evidence pointing to Fredo indeed set out to harm and injure his brother Michael, for the Donship and the fact remains “He betrayed his brother for personal gain”
Michael could have easily continued the same arrangements of keeping Fredo under watch or similar until Mama Corleone's natural death Michael had the money and the resources Michael could have spared Fredo Besides if Mama had lived longer....
