The basis for Stablegains' rate is Anchor Protocol's yield. At the time of writing, Anchor yield is set at 18% - 20% APY and expected to remain so for a long time. There are also other protocols that can offer comparable returns, which we might use to offer users diversification. The difference between those and the 15%+ we pass on to Stablegains customers is captured by Stablegains and used to pay your transaction fees and our bills and operating expenses.
We expect the rates of open finance protocols to beat those of traditional finance for a very long time. As for the 15%, while Anchor aims at holding their rates stable for the long term, we do expect the yield will go down in the future as the DeFi space becomes more mainstream. However, we do our best to find the best and secure rates, but maintain the right to lower rates when market dynamics no longer allow for such high yields. We will be fully transparent and notify all users in the event such changes becomes necessary.