Obviously, if you invest in stocks during a crash you will lose money. The major US stock indices fell over 50% from Nov 2007 to Mar 2009, though they were back to break even by early 2013.
Bullshit.
If you held stocks beyond 2013 (let's see, it is 2018 right now so that would include almost all of us) then you didn't lose money. So, no it isn't obvious that if you invest in stocks during a crash you lost money.
In fact the exact opposite is true. If you invested right at the peak back in the fall of 2007 and simply did nothing you made a bundle of money. If you continued to buy stocks you made even a bigger bundle of money. Fall of 2007 was a good time to be buying stocks.
One could argue that gold fell at most 35% over that time period and recovered faster, so gold was a better investment than stocks. My friend bought silver over 2007-2008 and was very happy with it.
Your friend has low expectations. In 2007-08 silver was hovering around $14/oz. Today, it is around $14/oz. Congratulations? Oh, and don't forget to adjust for inflation.
If you cherry pick time periods, you can "argue" virtually any investment is better than stocks. However, over any reasonable holding period (Holding periods like people here who are interested in a a lifetime of wealth have) gold and silver appreciate at about the rate of inflation. That is true as long as we have financial data, going back to Roman times.
The only way to make money with gold and silver is by trading it. Buying when prices are low and selling when prices are high. Possible in theory, but the number of people who do it successfully and can prove it might be very close to zero.