You have a very small chance. But by the same token you have a chance against Superman, Green Lantern, or Wonder Woman.
You are, in fact, dealing with the world’s greatest detective. A detective who does, in fact, know his limitations.
Your assumptions seem to be based on the idea that Batman is a complete idiot.
Batman will not get into a fight if there’s a significant chance he’ll lose unless he can’t help it. He fights dirty. He finds out as much about his quarry and any potential battlegrounds as possible. He knows when to get help. (Robin, Nightwing, Oracle - who is also useful for the previous steps - the Outsiders, the Justice League…) He’s equipped with weapons, soft body armour (and hard body armour per Miller), and top-level fighting skills.
If you get the drop on Batman, you’re either very good or very lucky.
By your own logic, Batman’s survival isn’t impossible even if he didn’t have all the advantages he has.
You think you have a chance against someone who has you outclassed and outgunned on every level?
So does he.
On the other hand, he does what he can to put the advantage on his side as possible. And he does have most people who doesn’t have Superpowers outclassed on every level.
There’s a few mere mortals who can own him, but they are, on the whole, on the same side - or at least believe he’s useful enough to give him free reign. Batman’s yet to deal with any of the exceptions without a more powerful ally to even the odds. Lex Luthor (who, despite being a mere mortal is a credible threat to Superman), the Ultra-Humanite, or quite a number of others could take him, but they don’t deal with Batman as an individual. And the reason they can take him is they have all the same advantages as him - they’re smart, they have access to major resources (including people to do their fighting for them if they don’t have the same ‘peak of physical perfection’ advantage - and the brains to use them rather than taking him hand-to-hand.). The major thing that keeps them from taking him is that a) they have no motivation to go after him, specifically, and b) he knows when he’s outclassed and will leave or call in backup (preferably both) when he is, rather than relying on luck.
Of Batman’s personal villains, the most credible threat in a fight is Ra’s al Ghul. Ra’s is smart. Ra’s has significant resources. Ra’s is in amazing physical condition. He knows who Batman is, so has a good chance of taking him unaware. But he also has a daughter who is very fond of Batman, so killing him would not be to his advantage. He has taken him a few times, though.
But Batman’s enemies - even Ra’s - aren’t threats by being able to take him in a fight. They’re threats by being able to cause trouble before he can find them.