Also, the packed stadium looks good on tele and it seems their main aim is to bring more women into the stadium, which is a very good sign for women's cricket or women's sports in general.
For the initial 2-3 years, maybe BCCI can toy with the idea of providing free entry to a limited number of fans (especially students). But gate collection is not that insignificant. I don't know how much the tickets for WPL is going to cost, but IPL tickets are priced from ₹800 to ₹35,000 (for matches involving Mumbai Indians at Wankhede stadium). Assuming an average of ₹2,000 per viewer, if 25,000 fans attend the match, the gate collection will amount to ₹50,000,000 per match. After tax and all the cuts, it should be enough to at least pay for the security and other expenses. And don't think that people are not interested in women's cricket. There is a surge in popularity within India recently.