Watched it. I have a counter argument. He said “ we kick those bastards off the network, rework the protocol around them”
Then the attacker will simply join the forked blockchain again and continue to double spend again. The amount of power needed will also be a lot less this time. How are you going to rework the protocol around them? You can’t.
What is the incentive for a 51% attack? I don't want to go into techincal details because you don't seem to be well aware of the basics, at least judging by this part you mentioned.
If you have unlimited free energy, you don’t have to have 1 million ASICs to launch a 51% attack. You would only need one giant ASIC.
But I'll tell you how wrong you are economically
It will be expensive. But, the return on investment is much higher. ~
The return on investment won't be great - it's the opposite, it will be the best way to burn your money, 51% on BTC is technically a possibility there is no doubt about it, but you will need at least a (rough estimate )1 billion $ to attempt an attack of such kind, so if you don't double-spend that same amount of money then you gain nothing, I am not sure how would someone spend 1 billion in a short period of time, you deposit 10% of that amount in any exchange and it will be stuck there for a very long time until they are done with all the KYC stuff, let alone liquidity issues.
The next thing you need to solve is doing this silently without brining any attention, because the moment you do, everyone will start asking for a dozen confirmation, and by the end of the day you will end up with worthless mining gears because an attack on bitcoin will bring it's value down.
The attack is doable but surely not for the purpose of profit, you will do it just to hurt bitcoin.