It's a combination of things.
While we work for our income,
most scammers, do not, so they have time, to plan elaborate schemes, to con people out of their money. Some are even too lazy to think of their own scams, and copy cat other people.
Why would you work hard, if you can easily scam other people out of their money? Laziness & Greed.
Well and then you get people, who do it for the kick. {
Example - White hat hackers, do it, to see if it's possible, but they repair and replace what they have done, and get nothing out of it, sometimes they even report the vulnrabilities, but then you get the script kiddies, who write no code, just copy someone else, and then boast about their hack, amongs their fellow script kiddies, to feel important.}
We will always have people who believe in hard work for money, and those who will lie and steal to get to the hard workers money.
Only thing we can do, is to expose them early and then to report them, for everyone too see.
If you find scammers here, report them here -->
https://bitcointalk.org/index.php?board=83.0