General Discussion

He was a calculating, charming chameleon who could read weaknesses, and always seemed calm and reasonable.
He had a knack for collecting people across a wide range of interests. He cynically appeared to be attentive and sympathetic
He could turn himself into "that guy" if you needed a plausible opinion or access to others who also used him, without even knowing why he was being used by them. He got wealthy being "that guy".

Since he started out as also being a charming pimp for bored young middle class girls wanting access to a glittering world above them, he could go even farther than if he just played the financial games like other mathematically clever young men who got access to the private school system.

He didn't care how he got what other people wanted. He just made himself indispensable to them. He made it okay for them to consider asking him for any secret desires they had.

And that is exactly what a Devil does when it walks amongst us mere humans.