If someone says something and then says "it was a joke", "it was a game", "I was just making a point", that doesn't cancel out the words and their impact - social atmosphere is not an intellectually pristine environment. You will change the atmosphere by yelling "fire" in a crowded theater and once it's done, there is no going back.
Likewise, if we dismiss someone's statement because "it was attention seeking", "they didn't really mean it", "something was misunderstood", "it's just part of the culture", that also doesn't cancel it out.
There are plenty of young, impressionable folks who latch on to ideas unthinkingly because they cannot take anything seriously at their age and level of maturity. But that is not usually the case with a 32-year-old adult like Shkreli, or people in hiphop culture, or people in actual street gangs.
Posturing language exists to make a claim to credibility. It serves a real purpose and is used in an instrumental way, for the purpose of conducting business on the terms of those who use it. The people who exploit this language the best contain in their personality some particular combination of motivation and lack of restraint, enabling their threats to be real to some degree.
Shkreli already displays such a personality among multiple facets. There is no reason to deny him the possibility of simply being a bad human being who is in need of careful monitoring by society.