From our zoom discussion last night, here is another way of asking the question:
The average person likely presumes that "the highest pleasure," is what we might call "ecstasy," and Epicurus says something not far from that in U423 (from Plutarch) where Epicurus says that the meaning of good is the near escape from some disaster, which I think most people would consider to name a condition of jubilation at having been delivered from a calamity.
If ecstasy / jubilation is what most people - and even Epicurus - seem to identify as a specific condition of extreme pleasure, then why isn't that also "the highest pleasure?"
That's the normal approach that Cicero and Plutarch think the world will agree with, and they are probably right.
Why should that line of thinking be considered to be incorrect? Why is "Ecstasy" not the highest / greatest pleasure?