Superheroes are real. There seems to be some kind of virus going around that grants people super powers. At first, its great, crime nose dives and society flourishes but soon it becomes clear that the superheroes have an addiction to saving people, the virus causing them to become adrenaline fuelled praise-junkies always in need of another high.
Some even start engineering crimes just so they can stop them, funnelling their wealth back into crime just to feed their addiction, but it becomes obvious to society that S3 or Superhero Satisfaction Syndrome is becoming a real problem and needs to be stopped. Superheroes are tightly controlled by the government and kept in rehab camps, carefully monitored. Newly created heroes that haven't yet been consumed by the addiction are allowed to operate under strict supervision and often work as guards for the ageing populace of junkie heroes, making sure they don't break out and cause havok.