The main fuel is the internet , followed by mobile phones and social media.
AI definitely makes the scams more believable, a Nigerian Prince can now easily forge documents.
But at the same time AI is a double edged sword, it can be used for both offence and defense.
the point though of a proper scam is to filter out the believables and find the guillibles.
You don't exactly want convincing evidence; you want a good story.
The main fuel is the "need" to have browsers that can execute code, coupled with the ability to transfer money via the internet. JavaScript was a mistake, e-commerce was a mistake, and so is everything else that came after.
Let's ask Vint Cerf whether the web was meant to run logic, or just be a document format. I bet no matter what he answers, the world would be like the GIF pronunciation "I don't care if the original creator said it's pronounced like giraffe, I'm gonna say it like gift because I KnOw BeTtEr"
Internet 3 when (because I know that academia does already have an "Internet 2", although I bet due to Internet 1 security issues, Internet 2 is already compromised too)
It's been used for defense for a long time. AI is why spam filters started actually working in the 2000s.