Obi Wan steals Anakin’s studs –
Being on a higher plane gives you significant advantage over your enemy simply in many ways. In real life it gives you a far and away significant view of the landscape. That information that can crucial on how to approach a fight or simply what decision to make.
The person(s) on the lower ground has less information to work with. The steeper the hill or mountain or valley is the harder it is for your enemy to move towards you and even perform basic attacks. You are at an awkward angle and the enemy can move around freely while you can not.
Imagine trying to play tag with a guy who’s at the top of a hill and you’re trying to run up the hill. It’s hilariously difficult to keep up with that person who can freely move around. While you’re stuck moving upwards in one straight path.
In Anakin’s case he had very few options on how to approach this. He could not disembark the machine he was on because the floor right in front of him was literally molten lava with a bit of rock. If you notice when he’s slipping towards the lava, his legs go on fire even though his feet aren’t actually inside the lava. It’s just so ridiculously hot that you will be burned by even being that close and having your cloth touch it.
Now Anakin knows he can not just jump off. His only choice is to fight from a distance or jump closer forward. However, Obi-Wan is cutting off Anakin’s available path to jump too. If he jumps too close his clothes and flesh will burn but if he jumps too far he risks being put in a terrible position right in front of his enemy and valuerable.
He can not turn his back on his enemy beacuse the threat of a force push or pull is too great and he can’t simply just walk ”float away” on the machine for that same reason. He’s stuck in place and must make a decision on how to continue to the fight.
Due to Anakin’s Arrogance he decides to jump over Obi-Wan and claim the high ground for himself. Putting Obi wan dowards to him so that Anakin could swing downward and continue the fight with him at the advantage. Obi-Wan anticipates this and warns him that he isn’t capable of doing this. He fails and rolls back down the hill.
The high ground gave Obi-Wan all the information he needed.
Anakin could not retreat, he could not move forward properly and only had one choice and that choice was reckless. Thus Obi-Wan winning from the moment he gained an elevated plane which the enemy had no other way to approach except move forward.
There is an argument to be made that perhaps Anakin could have used Lightsaber throws or force powers or another method in order to close the gap a bit better but given Anakin’s reckless nature. It was only natural for him to do something so daring and foolish. Obi-Wan surely knew this and exploited it to end the fight quickly