I know we wouldn't reach to Goldman Sachs for advise in cryptocurrencies, however we can't deny Bitcoin is on a bubble. We are inflating the bubble with huge sums of money while Bitcoin doesn't really change and improve it's technology at the same rate.
Wrong! We are improving. How much did it cost you to send a transaction in December and how much does it cost now? We have segwit, updated wallets, lightning in the end phase of development, and most importantly we have a much wider adoption. The economy is growing = the price is growing. There's no bubble!
Goldman Sachs advisor says 'Today's Cryptocurrencies Will Go to Zero, But Stronger Digital Currencies May Still Emerge' and this time they can be right. And pretty much is okay to relate today's situation with dotcom bubble back in the 2000's.
Sure, they may go to 0 one day, but what he failed to mention is that it may take 20 or 30 years. At some point very little people will want to use cryptocurrencies, just like at the moment very little people use cash for huge transactions. You just don't see people walking around with bags of money when they are going to buy a house or a supercar.