This is a common take from before Ohtani's statement today, but imho doesn't hold up anymore. Ippei was Shohei's main conduit for any information in English. The ESPN interview was given before the game, but wasn't published until after. It tracks that Ohtani may not have known anything until, as he said, something seemed off with Ippei's postgame speech to the team.
The widely reported (estimated) number from last year's endorsements was $50m. Until a few days ago I assumed it would be higher this year, but anyway -- you've mentioned his merchandise revenue a few times but I don't think players get a cut of their name-specific merchandise sales, do they? This may be outdated info but last I knew except for sales within a certain radius of a team's stadium (which go wholly to that team), the revenue is divided evenly across all 30 teams. Players get a cut of that, so sure, your overall point that he's making a lot in non-salary income stands. But if you are intending to say that revenue from sales of Ohtani jerseys accrues specifically to him, I don't think that's the case?
As for the rest -- really, you're just making wild speculations. Which is your right in this thread of course -- you're certainly not the only one -- but it's perfectly conceivable that he got good advice about the contract but still got robbed by Ippei. The two things don't have to be remotely related. Why would, for example, Nez Balelo who was likely heavily involved in the contract structuring, be looking at all at his financial activity? The things you're speculating about are all within the realm of possibility, but they are not what I would call logical conclusions.