The Basic Attention Token is unique because it is a payment token for running advertising campaigns through Brave Ads. As of November 2020, advertisers must commit to a minimum advertising spend of $2,500 per month to be able to launch their campaigns, but a potentially lower-limit self-service platform is currently in the works.
Currently, this advertising budget must be paid in full with Basic Attention Tokens, which advertisers can obtain from various third-party exchange platforms. From here, Brave takes a small commission, and the rest is distributed to publishers and users, so people prefer this, with small commissions but many people preferring large commissions but less demand.