It is very important to set aside greed if you don't want to be scammed by scammers because greed makes every offer look real and gives the impression that one doesn't need to miss the opportunity.
When some people come across a scam, their instinct tells them it may be a scam, but they have the confidence to take a step to try what it is all about, thinking that if it is eventually a scam, they will be able to run from it. However, in the end, they still get scammed.
You're absolutely correct. And the problem with some of these folks is that they wouldn't even acknowledge their actions as being greedy, they'd rather see themselves as people who are taking risks. I have a friend who is so deeply into Ponzi schemes, he'd always jump at every single earning opportunity without first conducting an extensive research to know whether it's actually legit or not, and when he's asked, he'd say that he is simply taking risks and that life is all about risks, that's usually his comment when you try to talk to him about the dangers of his actions.