There isnt much to defend against here. The guy sells silver for a living, and he is obviously a brainless PM fanatic like most of them are.
All I know is that I stacked some PMs a few years back and am doing well on them... but my crypto holdings have absolutely blown those gains away!
Let him snakeoil his silver for the next 20 years, which will go up slowly to match inflation, whilst we blow him away with the investment of a lifetime. His dumb ass will probably move to selling btc in the future when silver hasnt gone to $2000 but btc has