You missed the Carry Cost, its almost equal to as if you took a loan for the rest amount, there’s content availableon google on carry cost. Factor that in plus the taxes as now it would be short term gain.
Futures are at a premium. So you will lose around 60 to 80 points every month. Plus there is rollover cost, brokerage, taxes etc.
Instead what you can do is pledge index funds or nifty bees for margin and sell deep OTMs only on the expiry day. When I say deep, sell as deep as 3 percent away from strike on both call and put. Also, do it only on the expiry day to avoid overnight risk.
Collect may be around 4 points in agreegate. After all expenses you may make around 100 rupees per week. So totals to around 400 per month. Funds required per lot would be 1lakh. So that’s 0.4 percent per month. This works to 4.8 percent per annum. So this return is in addition to whatever you get from nifty.
Since you already hold index worth 8.5lakhhs. Sell futures. You will get around 60 points every month. Plus you can sell deep OTM puts. If you do it together margin required will also be lower since it will be considered as a hedged position. You can collect around 100 points per month.