This is an expression often used when a personalty experienced an unpleasant event!
When used accordingly,this expression is as proclaimed !!
To the negativity impacted, events ought to teach lessons , which explanations and moral persuasion alone may not achieve because humans are seldom objective in their perspectives. But when an inventory is practically impacted and such experienced , the lesson taught thereby, though not academic is ingrained in the psyche, to be cognized to avoid a repeat in the future!!
A practical illustration is when a kindergarten's fingers are hurt by flaming fire, he/she would be experienced in such a manner never again to play around flaming inferno.
How do you want to be taught? By experience or by instructions? The choice is yours , but the former always comes with a costly price!!