10 Years before, US interest rate 2%, Rupee Dollar Hedging cost 4%, so cost of money for FIIs is 6%, Indian markets used to give about 12%, so it was lucrative for FIIs to invest in India.
Now, US interest is 5%, Hedging 4%, so cost is 9%. On top of which FIIs have to pay 12.5% Capital Gains Tax, so it is not worth taking risk just to get 1 to 2% returns in dollar terms.