I think some scams are obvious, like the guy who messages you on fb out of the blue. Unlikely that this works very often, but presumably they are doing huge sweeps, messaging hundreds of people every day to get maybe one response. The people who get caught up in those kinds of scams are likely very vulnerable in some way.
Then there are scams that are harder to see through. The guy I fell for in my twenties was handsome, funny, intelligent, and I thought we had a future together. He didn't ask for money outright - at first, he paid for everything. He emotionally manipulated me into offering him money. In the end, he raped me, stole from me, and stalked me when I left. Despite all this, it was very hard to end things with him and I was traumatised for years.
I don't think I was stupid or gullible. I was just young and wanted to be in love. I was vulnerable because I was travelling in a different country. I wouldn't fall for the same kind of scam now, but maybe I would fall for a different kind of scam that was preying on my current weaknesses.
If I were going to scam some of the people on this thread, I'd be appealing to their no-nonsense nature, how intelligent they are, how brilliant they are to never be fooled, etc. I wouldn't ever ask you for money. But I'd work out how to get you in to the point that you'd be begging me to take your cash. We humans are very susceptible to flattery and to getting what we want. All I need to do is find out what you care about and what you lack. You care about being smart and unscammable. Okay, that's half my job done for me.