The odds are too low, some other sites has 1.8X-1.9X. If you raise the odds rate, more people will come to invest/bet

My signature site also has binary option and it has 1.8X, although I still think it is low, I would play there. The reasonable rate IMO is 1.95X, with 5% edge. It is more fair to investors. With so low payout people would play dice instead.