Because people do not learn from the experiences of others, until they start to get scammed on their own. And tell everyone that yeah, scams are real and everyone can be a target.
It's the nature of people not to easily believe on others, especially if they have not tasted it on their own. And sometimes, due to overconfidence and belief that, I am smarter than them, therefore it won't happen to me for real. But only to find out in the end, that you can also be their new victim.
Reality is, no one is excused from the bad guys around, no one can avoid getting scam even if you're completely aware of it.
I will agree with some of your points highlighted here, literally, some are not happening just because of ignorance actually, but due to thier behaviors,emotion and also overconfidence causes all these. Yes some people actually know that what they want to do is risky and many people have fall victims and they keep on doing it, which make some of them a dull till today either newbies or some claimed overconfidence members.
Honestly speaking, some people clearly ignore good advices, while some people repeat the mistakes they made before without learning anything from their past experiences. In some cases, some people actually assume they are over smart to be scammed or convinced,and that make them even more worse, and also a common negligence by not verifying any information properly or rushing themselves to take decisions can easily lead one to be scammed. However anyone can be victim if really we acts carelessly or when we are out of mind due to some pressures. That's why it's better to be thinking critically and calm patiencely. Lastly, let's stay at alert and continuesly active on upgrading ourselves ahead of the scammers, because if you're not informed you will be deformed.