And Fredo -- well -- -- Fredo was -- well -- was deemed weak and stupid to be the Don.
I too reckon, Fredo is even more cunning, devious and ruthless than Vito and Michael put together! and Vito may have picked the wrong son! for Donship

recapping -- the facts remain,
“He betrayed his brother for personal gain” whether “unwittingly [or otherwise] Fredo was involved in a coup attempt” which could have wiped out the entire Michael Corleone family

Fredo “gave information to the Family's adversaries, opened the drapes [thus identifying] Michael and Kay's bedrooom” which was used to attempt the hit

We can't ignore, his outburst I'm your older brother Mike and I was stepped over! It ain't the way I wanted it!

Fredo was seething with jealousy and resentment, so consumed with being stepped over
and he can only get the Donship if the current Don was dead or sent to prison

The Donship was brought up (explicitly) in his outburst and I reckon, is really the issue that he may feel will get the respect that he so desperately craves, for him.

“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

If he had volunteered the information he knew about the Senate hearing which he deliberately and deceitfully concealed even after his betrayal, the Tahoe shooting then "redeeming feature." perhaps could give him the benefit of the doubt but he cunningly withheld it, for Michael to commit perjury and sent to prison, to become the Don-:


True Pete Fredo was the only contender with “the motive and the incentive” for opening the drapes “because he was cooperating with Ola against his brother”

Look -- we are all reasonable Godfather fans here; That was my two cents worth but interested in others' perspective, interpretations / speculations as to,
1. who else had the motive and incentive to open the drapes
2. what was his “little help” -- it'd be good for the family
3. what was “something in it for me -- on my own”
4. why bring up the Donship (explicitly) in his outburst if he was not after to be Don
5. what was he doing cooperating with Ola against his brother” in the first place
6. why did he deliberately and deceitfully conceal the Senate hearing
7. why did he cunningly withhold the information he knew
8. why was he seething with jealousy and resentment, so consumed with being stepped over if it was not an issue
9. how Fredo, opening the drapes to Michael and Kay's bedroom on Johnny Ola's orders, did not have nefarious intent

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