It doesn't matter how long it takes before people understand Bitcoin properly. Why?
These are very common reasons I hear from people around me;
# It's a ponzi scheme. (No matter how much explaining I do, they don't change from the way they see Bitcoin)
# Volatility. (I can agree that this may play a role of importance, sure)
# Bitcoin as currency? Why would I buy Bitcoin to pay for things, while I can pay for everything right now already? (Once again I can't blame them)
# Who is in control of Bitcoin to see if everything goes according the rules? (They fail to understand that there isn't a central authority needed)
The only thing they see as being interesting, is that when the price will fall back to $100-$200 that they will jump in, and sell at a massive profit as soon as the price increased again. If you tell them that it's highly unlikely that Bitcoin will go back to such levels due to the growth and demand, they just turn their face like you're talking bs. I even adviced certain people close to me to invest while the price was sitting below $500 not that long ago. But still, they wanted to wait for the $100-$200... Ignorance from the highest levels.