Interactive Brokers has an internal prop fund, Timber Hill, that uses the trades happening on the brokerage to execute their trades (its a proprietary form of liquidity - every major electronic brokerage does this). Basically, you aren't just paying for the trade you are also paying for it in that you don't have direct access to the markets and IBKR will front run you before your trade is ever executed. Its like an implicit trading cost thats hidden.

Volatility trading is more math-focused, but requires discretionary trading as well. Its less automated, and requires more specialized knowledge than other strategies. Volatility strategies aren't run by random people coming out of school or other industries. They are almost always run by a trader with a very well developed back-end including a quant (who is trained in volatility modelings - not as easy as the books lead you to believe) and still a very sophisticated trading system with access to both the options exchanges (which are unwieldy) and "normal" equities exchanges.

Its all possible, but can you make a living at it? Its a big maybe. Can you actually make more than your normal job or even a fraction if you were with a well endowed quant fund? No way. Not unless you have been in the industry for a long time.