True, friendly matches are just for experimenting and it is too risky to bet on that matches. I personally, rarely win when betting on friendly matches, because every team never serious. If Bayern Munich are serious of course they can win and maybe with a big score, I also believe that. But considering that this match was not an important match, they did not do their best to winning.
We all bet here for only one goal, namely winning, and of course the seriousness and performance of clubs in competing is the reason we favor a club to win, whereas in friendly matches, we can't find serious games because it won't have a significant impact on the trophy
as well as the position in the team standings, friendly matches are only a place to test the young squad and reserve players and clubs will not try to play seriously because it will only make their players tired and could result in injury, betting on friendly matches is clearly not a solution to betting because it will be difficult for us to predict who will win and usually friendly matches are often used as an arena for score manipulation by high-class bookies.