It is undeniable that most people are deceived because they do not have a social environment and do not have knowledge so they are easily trapped in fraudulent syndicates, especially if the economic conditions are not good, it is very easy to get trapped. On the other hand, why people are easily deceived apart from the knowledge factor, also because of the influence of emotions that cannot be controlled.
With knowledge and social environment we can protect ourselves from fraud, because of course we can recognize the signs of fraud, verify information, and be more careful in taking information so as not to provide personal data or be tempted by quick money schemes carelessly. Nowadays, there are so many examples of fraud that often occur in this era, starting from online fraud to offline fraud, so always be alert to anything suspicious.
Social environment may not be enough or it depends if what type of people are there because what if the people that are there are also less knowledgeable and only talks about nonsense? We still can't learn any valuable lessons from them. The issue is more on personal, though I think you got a point that economic conditions can also influence it because if the economic conditions are not good, that can also mean that there are less jobs available and the pay rates for them are only less.
The prices of the goods are also increasing, etc... so people are becoming desperate of finding a better solution to this problem that they can end up joining shady groups, or can get trapped on it easily (this one is not intentional). You mentioned emotion there but this is still related to it. I mean if only things are already much better, the emotions of the people are also much stable and better as well, making them to decide the right things only.
Fraud is not new and it started actually in the offline world because there are still no internet back in time but now that we have it and almost all of us are relying on it, no wonder why there are now lots of frauds as you said. We can still use the internet to gain more knowledge and counter them.