The problem is that what it takes "negatively affect the rest of your life" depends a lot on what role you have in society.
Short of pornography producer, fantasy fiction author, songwriter and other professions where copious drug use fit one's "brand image" or potentially enhance one's work, a tenured college professor gets about about as much leeway from the rest of society as a white collar professional can get. He can be "eccentric" and nobody blinks twice. But for other professions the standards of behavior are different (and generally get more permissive as you go down the economic ladder).
Defining the difference between acceptable use and addiction, and by proxy who's problems are bad enough to be considered problems and therefore in need of solving in a way that is relative to one's place in society is very dangerous. If you're blind in one eye you're still blind in one eye even if it doesn't negatively affect you. Addiction (and a multitude of other conditions) are the same.