If only it was as simple as that. Overall our clients lose more to STT , other govt charges +impact cost than they do to the markets. So taking positions against these will just mean more charges and impact cost. Also most retail buy options, so going against them would mean shorting options. If retail is wrong, limited profits - but whenever right unlimited losses. This doesn’t make any sense at all especially when every trade is coming with huge costs in terms of taxes and impact.
But like I said earlier, if there was a way to execute these trades by being counter to every client trade without having to pay taxes, impact cost, etc (like in CFD platforms, darkpools in the US, forex trading, etc) then maybe it does - but only until a black swan event hits you.
The recent one which shut down many CFD and forex trading platforms was when swiss franc was unpegged.