-snip-
Wagering on pre-season games is definitely not what we expect to happen, in positions to forecast accurate predictions. In preseason games, elite clubs mostly lose to average clubs, that's totally understandable, and it doesn't even surprised me, ready to face the outcomes of these games. In pre-season games, it's consider not important and players do participate for fun. On the other hand of the coach, he utilized his players, giving gametime opportunities for every players in his squad, also a means of selecting the first XI when the season begins.
Pre-season matches are outside the context of the Champions League, so maybe it's not constructive enough to continue the discussion. For Champions League matches, I rarely even bet on qualifying matches, it's too risky for me considering there aren't many teams I really know.
I prefer to bet after the group stage starts until the final match. It's a more reasonable way to earn bets while entertaining yourself with a great game. For next season, I hope Manchester United won't let me down too much in the Champions League. They performed well last season, so Ten Hag should be able to maintain the quality and performance of their team next season.