If you were told the outcome of a soccer match, hours before the match was scheduled, and you were assured that it would 100% win, how much would you be willing to bet on it? Assuming it was a 100% cant lose situation.
I do not think there it is possible that there is any situation that is a 100% can't loose situation in gambling, this is my conviction, and with that, even if it is a hypothetical situation that you have stated that there cannot be losses, I still will want to play it safe due to my already strong convictions and still risk an amount that I can afford to loose. I will not go all in like most people will.
Maintaining discipline in gambling is important. You must learn to have strong convictions so you are not easily swayed by the promise of sure games and big wins. Always play it safe.