It is hard to point down number of methods on how to make one million dollars a day legally, without specifying it's initial investment and risk.
One of the scenarios on how to make it (or loose it) is not neccesarry Forex or Digital Options but fixed income market.
DV01 bonds ($ value per 01%), are the ones that been in tresury for more than 30 years and can give yoi more than $2 000 per each milion invested.
If you become a lucky investor of $509mm worth of DV1 bonds, they would be worth 509 x ~$2 000 = 1 018 000.
If the DV1 treasury note go down by 0.01%, our lucky investors bonds will make milion dollars in one second, during normal trading hours. During certain events, the gap might be even more than 8 basis points in microtransactions as algo-trading will take over.
Example? Buy 3 milion shares of Coca Cola, with is worth around $120 000 000 and you will get more than million dollars each three months.