BAT token:
Total Supply: 1,500,000,000 BAT
Circulating Supply: 1,273,006,300 BAT
There are: 227M BAT to distribute
And it is not just unminted BAT for reward distribution, but from company, who want to promote their project/product on Brave browser. I think they need to buy BAT token from market to pay Brave team, and Brave team can use their BAT to distribute browser users.