cdb03b: They evolved in a region that had that terrain and survival dictated that they become skilled at that type of thing or they would be eaten. Those that were not balanced fell and died and eventually those with the skills were the ones that reproduced and the entire population obtained the skills.
PastelFlamingo150: The interiors of their hooves are softer than the exteriors, creating a suction cup effect. Also, walking on 4 legs instead of 2 is more stable and lowers the center of gravity.
ToedInnerWhole: You have multiple levels of explanation for a question like this:
What in the development of a goat makes it good at balancing/fearlessness?
What mechanism gives the goat good balance/fearlessness?
What evolutionary process led to goats having good balance/fearlessness?
Why did evolution lead to that process?
Since you didn’t specify, I’ll answer them all to the best of my ability:
Development: Practice, familiarity, goats do it a lot so they get good at doing it. Go watch a video of kids playing, it’s very cute.
Mechanism: Goats likely have very good inner ears for balance as well as strong leg muscles for it.
Evolutionary process: Goats that don’t have good balance are more likely to fall down the hills and mountains they live on and so more likely to die and not have more kids.