dYdX has been building a business model around the exchange. We introduced maker taker trading fees in March 2020. Our goal so far has been to earn consistent revenue as a company, and incentivize provision of more liquidity on dYdX protocol.
You can read more about our business model in our official announcement here: https://medium.com/dydxderivatives/the-dydx-business-model-6689aeb1cbde#:~:text=TLDR%3A%20dYdX%20is%20building%20a,of%20more%20liquidity%20on%20dYdX.
You can read more about our authors here.