Why would someone make a mistake? Why would someone do something wrong?

I don’t believe anyone would do something “wrong” intentionally. I believe they would only do what they imagined would be for the best.

Some examples:
– Tripping on the stairs
– Slipping on ice
– Slighting a good friend/relative
– Committing a heinous crime
– Failing to properly conceal a heinous crime

Questions:
Really, what is at the root of a mistake or a wrong doing?
For any imminent mistake or wrong doing, what would it take for someone to avoid it or choose against it?