"For lack of vision a people lose restraint, but happy is he who heeds instruction" (Proverbs 29:18) is a perfect description of Korach and the rebellion he led.
A bellicose populist, and overreaching Korach inflamed his followers to challenge not only Moshe and Aharon, but G-d Himself.
His manipulative use of mob rule and the price he and his followers paid is a harsh lesson for today.