It seems to me that the issue is not the length of the rounds. He has enough physical strength to jump-run for an hour or two, I'm sure of this, the problem is that Fury will constantly hit him, including in the body, and this will greatly reduce both Ngannou's speed and his endurance. As for Ngannou's blows, they are unlikely to reach the goal, but one blow is enough, so there are chances.
Of course, it is a big issue because UFC fighters are not trained to be boxers where they have to survive 12 straight rounds per fight or even in their sparring rounds, they are taught differently because stamina is not that big of a deal in UFC but in boxing, it is.
I know that Francis Ngannou does have a chance, but those chances are only much greater in the early rounds where his stamina is still at full level but when it comes to middle and late rounds, it will be a challenge to him to stay focused as he just cannot catch up specially against an experienced boxer where they are trained to preserve their stamina even if they are being hit constantly.
Maybe you're right, but still it seems to me that both boxing and UFC are both closer to a marathon/middle distance than boxing = marathon and UFC = sprint/medium distance. The only question is how you are doing in the ring. If you are a boxer and your wrestler opponent is dragging you down the canvas then you will get tired already in the first round (UFC). If you are both boxers but your opponent is constantly hitting you, then you will be tired long before the middle rounds (boxing). And I have no doubt that it is Fury who will constantly beat Ngannou from medium and long distances while remaining almost invulnerable.
I definitely wanted to make such a bet (Ngannou's victory by knockout in the first round) but now I understand that I will not succeed - too many people see this option as possible, which means the odds will be far from interesting.
I hope that if the knockout does happen, Ngannou will not “let go” of Fury and finish him off. Fury has good experience of continuing the fight from a disadvantageous situation (for example, he defeated Cunningham who knocked him down in the second round).
It seems most people think Francis has zero chance but that's why it's pointless putting money on Fury to win because the odds are shit and there's always the chance of an upset. I personally prefer high risk high reward and there's no excitement if you're not winning big. Personally I think Francis could knock anyone out on the planet and Tyson isn't going to be able to dodge everything Francis throws at him so its worth putting something on. If Francis can't get a KO though he'll almost certainly gas out.
Yes, I also hate small odds (like +10% at the risk of losing the entire bet). The bet on Ngannou here looks the only reasonable one.
You are right about Ngannou, but by the way, it is not known what shape the greedy belly is in, he often had problems with sports mode and I am not at all sure that he will be in good physical shape (especially when assuming that the fight will be easy).