Yea incredibly hard to do so consistently. Those that do (the hedge funds) have the security of the ~2% fixed fee they earn to weather the periods when the returns are not there aka "others peoples money".
You can if you have an enormous pile of cash. Then you can pat yourself on the back for making a few $k per month (which would only be a couple % apy) for acting like a quant when you could make the same amount in bonds.