It's the same shit the mainstream music was about back before to, it's not new. The Doors, Rolling Stones, Prince, Madonna, ACDC, etc. the moto has always been "***, Drugs, and Rock n Roll", money got involved during the Jay-Z, B.I.G materialistic lyric style and has went from there.
Also when people get to that status of being extremely well known, most but not all don't try as hard with there music. It's different when you're an underground artist trying to make a name for yourself on an indie label where you have to pay 50/50 with the label for everything, you have to bring it everytime if you want to eat and have somewhere to live. While mainstream artists have millions of fans who will love anything you give them, plus they're still making royalties from old hits.