That's humans for you. We all do some dumb shit. The same can be said about all sorts of things, such as lack of condom use and the contraction of AIDS and other STDs. The lack of cycle helmets being worn that only seem to be of importance when some one cracks their head open and dies.
A lot of people are absolutely aware of the risks but choose to ignore them in most cases. Even if there was a huge advertising campaign about the use of earplugs in clubs and live events, I doubt many would pay much attention. Look at smoking, for years they had pictures of rotten hearts and lungs on the boxes of cigarettes to display what happens when you smoke, but people still bought them in the millions.
It's a step in the right direction and more awareness has to be promoted, but unfortunately it's ultimately up to the people to listen. It's only if earplug use became cool in some way that anyone would use them, because deep down that's all that anyone really cares about. It's ultimately why other safety equipment is not used; people not wanting to stand out and go against the grain. It's pathetic really when you think about it.