Decadence, or what people refer to as decadence, can be a fun thing, hedonism, indulgence, but there's an older sense of the word that I think is not completely obsolete. It's the kind of decadence signifying corruption and decay that's associated with court life in 17th century France under Louis XIV. Young aristocrats drank, ate, screwed, without any limitations whatsoever, but what makes it a decadent period, in my opinion, is that the happiness of that time probably masked severe frustration and limitation.
France under Louis XIV was the very definition of an absolute monarchy: power flowed down from the person of Louis XIV and his household alone, power was not shared with anyone else. This was a problem in that the aristocrats of France had a tradition of being somewhat involved in the politics of the kingdom, in decision making, and in setting policy. Since there was no way to kill all the aristocrats Louis did the next best thing: required them to live in Versailles where they could have all the fun they wanted without having any potential of actually exercising any real influence. In the place of traditional offices Louis XIV instituted token and completely symbolic roles, such as the person who presented the robe to the King in the morning, who had the privilege of doing other mundane tasks, that the aristocrats filled and eventually learned to compete for. On the other end of the spectrum anyone who was perceived to be scheming against the King, or, to be quite frank anyone in the court who was ever heard to say anything negative about Louis XIV to the wrong people was dealt with very harshly. One male noble was heard to exclaim while drunk that Louis was really just a stupid country squire and that Versailles was just a rural manor house; he was ordered into permanent exile in the middle of nowhere, for the rest of his life. This is the background on which the decadence of the court took place.
So while the aristocrats partied, drunk, ate, and indulged themselves, they were no doubt aware that although they were having a good time they could not have any personal power besides being hedonistic as long as Louis XIV lived.
Looked at that way, one has to wonder if some of the debauchery was a kind of alcoholic consolation as opposed to a kind of happy frolic. Indeed, if you read de Sade, who although he lived roughly a hundred years after this time period seems to have embodied the ethics of it, you almost immediately detect a tension between a praise of hedonism and a belief that the world is fundamentally unjust, that the powerful exploit the weak mercilessly, and that the people who do this will never be brought to justice for what they do.
This dovetails with the experience of poor minority youth in the United States in that it seems that the 'gangster lifestyle' that many kids do choose to pursue isn't done so just because they think it's cool so much as because the traditional ways of social advancement in society are closed to them. Because of their skin color they experience hostility on a daily basis, they go to crumbling schools where they get next to no education, and they get no support when they want to do something like go on to higher education, despite all the bill boards and programs that may make it seem otherwise. In the face of all of this, the impulse must be to withdraw from legitimate society altogether and instead try to make a life for yourself outside of the law.