His point is that bitcoin can not be self-regulatory being that it is a decentralized system which means the market forces will dictates what happened. But, fiat system runs on regulatory mechanism, the central bank controls the supply of money(Ms). when there is bubble and it burst, the central bank will intervene unlike the bitcoin system.
Here is what i think, bitcoin can run and be able to self-regulate itself in order to avoid such bubbles.
bitcoin will be a subject of tools being manipulated by the whales and others. Something that is out of control will only be regulated by those that hold a huge amount. However, I believe the reason why he said crypto is a threat to the economy is due to massive adoption which he thinks due to volatility, people can lose money which in turn affects the economy. We have had many opinions in the past and I still maintain my stand that bitcoin cannot replace fiat in the future