Really?
Even if the party is completely incompetent it still seems there must be at least some chance that by a series of extraordinary coincidences they will win. Regardless of how low your chance of victory is if you have enough tries you will win eventually with probability 1.
No. Not if the infinite collection of universes is arranged in such a way such that you go up against successively more and more skilled competitors. If so, the probability of success on a given iteration could go down each time. If it goes down fast enough, the probability of success in the limit can be less than 1.
The current Goblins Comic is relevant.