Peter Schiff is absolutely right...sorta'.  No kidding, I love to listen to Peter and I do agree with him on almost everything.  Where we part company is over cryptocurrency.  While anything can be manipulated to be a Ponzi scheme (research the tulip bulb mania in the 1600s), and cryptocurrencies can be Ponzi schemes, the ones that aren't are very strong.  People forget that the main reason for money is trust.  Trust that the work it represents is really there.  

Gold and silver have held that esteem for a long, long time.  Now we still have to verify if the gold is pure.  Trust but verify!  Remember that term?  Well, the crooks are getting more creative and tungsten bearing gold has been popping up.  See here. The difference with cryptocurrencies, particularly Bitcoin and its descendents (Litecoin - LTC, Digibyte - DGB and my favorite Digital Note - XDN) arrive already verified.  There are no more steps.  You can't do that with gold, silver or any other physical.  You have to inspect it to make sure it's the real McCoy.  

There are a lot of cryptos that are going to be abused but, if you keep your crypto on your own wallets, you won't have that trouble.  The miners verify the cryptos as part of the process.  You receive it and you have the real deal.  

Privacy is another factor that can be obtained with certain cryptos.  Monero is famous for that as are a few other but the one I've decided is best is XDN - Digital Note.  They use special methods that are uncrackable like the legendary one-time pad encrypt/decrypt method.  Right now XDN is at the formative stage Bitcoin was in about 2011 or 2012.  Check it out.  Do your homework.