People are easily purchased
It’s not about being purchased it’s about the part of the person you know vs the rest. To Gotti’s neighbors he was the nice guy that hung out and held a party for them, sure on some level they knew he was different, but it’s a difficult piece of internationalization to have this conceptual knowledge you only have second hand override the experience you knowledge you get first hand. If he’s a nice guy to you directly and repeatedly you’re going to think of him as a nice guy, it’s how humans work.