RileyGoodside I assume you are going to make a profit by doing arbitrage trades between stellar and existing exchanges. I had a similar idea to provide liquidity to Tempo EURT by doing trades on Kraken EUR/XLM, but will probably not find time to do it.
In your case users would also need to create an exchange API key and give it to your application and have some balance on both stellar and the exchange for them to be profitable.
One big risk is that your trading algorithm would be public and if you know agains what algorithm you are trading it gives you a big advantage. Especially that trading on stellar would be a bit slower than traditional exchanges. It's a hard problem to solve. Can't wait to see what you make!