Because it's a process confirmed by it's fruits.
That's a good way to measure. Jesus did say, wisdom is proved righteous by its fruit. Looks like you are quoting Jesus.
Some fruit take a while to manifest.
For example, global warming is a fruit. Took years for persons to realize what they were sowing.
Lung cancer is a fruit. They aren't doing anything about cigarettes.
Actually, it would probably be nice if we could tell the smoker to stop killing us with the second hand smoke, which we never consented to... and they stop.
They usually continue though, and insist on their rights and freedom to do so.