Why don't Indian players play second T20 league?

IPL is the only popular cricket league where all the popular cricketers of the country and abroad will be seen playing together but have you ever thought? That what is the reason behind the popularity of IPL is actually the reason behind it is the contract between BCCI and Indian Cricket players in which no Indian player can play any league other than IPL league because BCCI is well aware that Indian players The craze is in everyone.  

all over the world and if they play in external league then it will give direct competition to IPL and popularity of IPL will be reduced so BCCI never allow Indian players to play in other league and hence in all IPL franchises they make lot of money spend on "Indian cricketers" so that they don't feel the need to play anywhere else guys, what do you think about this?  Do write in comment section