First priority is food, water, equipment (shovels), medical supplies, maintenance supplies, land, seeds, guns/ammo, etc.
If you happen to have enough wealth that you have money in the bank/mattress left over, then YES you want to buy physical gold and silver to preserve your wealth.
If you have more than 3 months worth of expenses stored in the bank, you should be prepared to lose a lot of money (which you woke up every day and worked 8 hours to earn). Ditto for cash. Most of your money -- your nest egg/stored value/wealth should be placed in something that can't just disappear because of a crash. That means the things listed in sentence #1, and precious metals.
But yes, it's foolish to put all your wealth into precious metals, lacking all the basics. You have to start with basic preps that are immediately useful.