And their target is people who're more stupid than them, either because they never experience got scammed or never learn from mistake.
For example, "Nigerian prince scam" (no offense for nigerian people) has been around for a decade, but even in 2019 it still rakes in over $700,000.
You are right, the people that are scammed behave stupid, but if we see it another way around, we may not blame them. People like easy to get profits and also what they do not work for but profit from it. Life does not work like that, I remember when I know about bitcoin, I looked online for how to earn bitcoin, pay-to-click site was one of them, I decided to work on one, from the ads that are displayed, was a bitcoin generator, in less than 10 seconds, it generated almost 0.005 btc and displayed a bitcoin address, that I should deposited 0.02 btc to claim the bitcoin generated. I still always remember that day if not because I had no bitcoin, I would have deposited it and expecting 0.005 btc not knowing it was a scam. What I noticed is that human are so ignorant of many things, even psychologically they are weak and decoy to those scam because they do not have the knowledge and experience. I blame more to our governments, they need to find ways thy are educating us to also educate people how scam is real and how to avoid. Afaik, governments are not trying in any way than to deprived people of their privacy and makes them more exposed to centralized bodies like Google, YouTube and social media, and in one or more ways be scammed. Humans needs education, forums like Bitcointalk can help but how many people are visiting the forum if compared to all the whole world, but I am very certain anyone in this forum can not fall for such scammers because even without being a victim, we have the knowledge than can not let us got scammed.