Blessing is less dangerous than cursing as it gives people confidence that they can get good fortune, become well again if they are sick their children or loved ones can benefit. Basically being blessed makes people feel that a higher power cares for them and is favouring them or protecting them.
In Christianity blessings come from God though other religions teach different systems for blessings. Televangelists encourage the faithful to give, give, give their cash
to put yet more into their already fat bank accounts to give to God. Then it is hoped that God will bless them in return. If the lives of believers become miserable or remain miserable without tangible evidence of blessings from God then the faithful believe blessings will surely follow in the Afterlife.
Adapted from a deleted RationalWiki article