People scam because there are many other people who allow themselves to be scammed, unfortunately. They make themselves easy targets by being careless, too trusting/caring, gullible, uninformed, etc. Many people get scammed because they, themselves are greedy and or lazy. They are presented with what appears to be easy money and fall for the scam because of their greed. If it sounds too good to be true, it probably is.

As long as there are greedy people to prey on, there will be scammers who will happily take advantage of them.