It doesn't matter how well you protect your gold, you can never protect its value, since this will be diluted if someone else brings a lot of gold to market. That's what happened during the ~1700s: lots of gold was brought to market because of world travel and disrupted local economies. Bitcoin prevents this by automatically adjusting difficulty. Asteroid mining can make gold useless, while Bitcoin would continue to function unless SHA256 is broken. I'm not saying Bitcoin is better or worse than gold, just that they both have advantages and disadvantages when compared.