While I agree with number 1 and number 3, it is more of number 2 that is the foremost reason why a lot of people are easily scammed. In a way, we are all greedy. We always want money. And if we already have it, we want to have more. That is basically human. It could be all right if in the process of wanting more, more research is also being done so as to make sure that the process of getting more is safe and near certain. However, it is where almost all of us fail. We do not do enough research to make sure we know the project very well before investing.

Trust is a lesser concern because it should only be a direct result of number 2 and nothing else.