Gold can't be lost due to a hard drive crash, and it cannot be stolen over a network. More importantly, I believe a majority of people (myself among the number) do not understand bitcoins were stolen from mtgox.
Besides, "understanding" is very slippery verb in this context, what do you understand about gold? You know where it all is? You know who is in charge of protecting it and who is the owner? You know its location? You know who is digging for it? You know where are they digging? I don't clearly see what "understanding" you have about it.
What I'm talking about: In India, my family buys a small amount of Gold every 3 months or so. Gold coins, each a few grams in weight. I know exactly where they are -- I have a safe deposit locker at my bank, and some of them have been converted into jewelry for my wife.