The charts might not show it well, but the fund is already around 25% off it's 12 month bottom.
I bought the minimum required amount of VGPMX a year or two ago when it looked cheap vs the market as a little experiment. Guess what, it is cheaper now, a lot cheaper and the overall market is higher, a lot higher. Given how little it is of my portfolio, I am hanging on to it as an example to remind me not to try and pick sectors, and as an exercise in patience to see if it will outperform the market when the (not) so inevitable correction comes. As others have mentioned metals (granted the index is not bullion) have not historically been a good long term investment. I will not be buying any more.
Market timing is psycologically taxing. Even if you do well, get it 60% right and outperform the S&P, you will still kick yourself thinking about what you "could" have had. That is one of the beauties of dollar cost averaging, it blurs your purchases and sales so much that removes the psycological burden of getting it "perfect", a real important point for mustachians that thrive on achieving optimization.