You can open a trading account and try to trade 1 million NDX or spx contracts. You should get an error message.
Open an account with a top-tier bank that also makes markets. You can get a ton of liquidity with time to fill and $Billions. Your overall friction could easily be $10 on up with market impact. You'll get massive regulatory scrutiny. If you're holding till cash settlement, it will save you tons. If you are really serious. Think about how the liquidity is created and do, at least some of it yourself.
Oil Crash Busted Broker’s Computers and Inflicted Big Losses Interactive Brokers users couldn’t trade when oil broke zero Incident will cost firm more than $100 million, chairman says _____________________________________________________________ Go open a small account with IB. Then try to trade millions and millions of option contracts. The platform should stop you from doing it. If your order gets through, and you suffer billions of dollars in loss, it seems like you are protected. The newbie Canadian day trader incurred $100 million loss because the crude oil price went negative and he was not aware of it. He didn't have to foot the bill even though he was partly at fault. ______________
When the mistake is extremely huge, traders really learn from it. Hopefully, traders won't end his life.
He is very specifically referring to number of contracts, in that he preambles it with position limits.