What makes a drug popular is that Big Pharma pushes their drug and it becomes mainstream. Look at Welbutrin...it was practically toted as a cure all. Big Pharma supplys all the studies and gives incentives to doctors for prescribing their drug. The new wonder drug always has its own 5 minute plug on TV every other commercial, you see it's name in every magazine, their name on every pen sign clock in doctors office...city buses, bulletin boards, web pages...

If a drug doesn't get an advertising campaign and go mainstream, it'll probably not get prescribed much.