I once read a thread about someone who bet millions of dollars just because of a small profit with low odds of no more than 1.05 and he was sure he would win and could win the match, but in the end he lost, learn from that experience so you don't easily trust other people when betting , even though the results are told by someone or even the dealer, so the most important thing is to play with your own analysis at your own risk because even if it is 100% accurate I will not bet on anyone's words
That's a totally different case, the guy who bet millions on a game did it solely on the basis of the team having the highest chances of winning the match, but in the situation given here, it is that you already know which team will win, and it is a 100% guaranteed win, which means it is either fixed or there will be some kind of cheating or something.
I understand that it is always better to do your own research and analysis before betting on sports games, but if you get a chance to get guaranteed returns on your bet, I don't think anyone would let it go, and the real question here is, how much would you bet if that happens?