Just a thought, if you buy 10,000 COSS (currently 7K USD) and it has 1B daily volume going through it per day (could easily become the norm for a typical exchange in the future) you'd be earning over 5K per week in revenue share.
Did you maybe miscalculate? With 10k COSS and 1B vol, the weekly income would be 744 USD. Still not bad, but not quite 5k.