The Angels arguably the two best players in baseball and are treading along barely above .500Imagine being the Angels trying to re-sign Ohtani. Conservatively, you would have $125 million locked up with 3 players (Rendon, Trout, Ohtani) with arguably one of the worst farm systems. That franchise would have been smart to try and trade Ohtani and Trout this season and start over.
It is obvious that they aren't going to succeed with the current roster and resigning Ohtani would only handicap them further. I think the Angels missed an opportunity to build for the future by not trading him.