Its really not a great arguement, he basically says it has no value because it has no value.
The dollar on the other hand has value because we all agree that it has value. Well that's the same for Bitcoin.

Share prices and commodities are the same, markets decide the price. You may find the market decided price to be too high or too low, but it is what it is, it isn't a scam!

Bitcoin might be overvalued, or undervalued, it isn't a scam though. It is a weird bubble too, if it is a bubble. It went crazy for a while a month ago, but now hasn't crashed. The next move will be interesting