“brought disaster.” Not only had 36 men died, but the hearts of the Canaanites, realizing the weakness in Israel, could well have been strengthened, and they could have attacked Israel en masse.
“Yahweh will bring disaster upon you...And all Israel stoned him.” This is one of the verses where Yahweh is said to act, but He does so through the actions of His people.
“All Israel stoned him with stones.” This may seem harsh, but about 36 men were dead because Achan and his family could not control their lust, and we must make no mistake, Achan’s whole family was in on the deception. Justice demanded the death penalty. The only thing as valuable as a human life is another human life, which is why God commanded the death penalty for murderers (Exod. 21:12-16). To demand less than the death penalty, though that is done regularly today, is to send the message that one life is more valuable than another; the murderer's life is more valuable than the life of the one he or she murders.
Achan knew that if he stole something devoted to destruction that he would be devoted to destruction too, because that is what the Law said (Deut. 7:26). Achan was a fool. He and his family took a chance that they could enrich themselves with things from Jericho, and it cost 36 innocent people, and then they themselves, their lives.
[For more on things that are “devoted” to God, see commentary on Josh. 6:17.]