The idea is that the Brave platform will allow users to send micropayments to content publishers. The micropayments will be in the form of "Brave Coins" which are like Bitcoins but specific to the Brave platform. The reason for this is that you reduce transaction costs to a point where it makes sense to send a $0.50 (or whatever) payment.
So if the Brave platform succeeds then you'll have a whole bunch of people who want to exchange cash for these "Brave Coins" so they can send micropayments. These early investors will hold all the Brave Coins and so they will get the initial influx of cash from people buying Brave Coins to use the platform.
Edit: Possibly the coins are being used by advertisers on the platform, not for micropayments.
My understanding is that the tokens (BAT) are sold to/for advertisers to allow them to purchase advertising on the Brave platform so that they can advertise on specific publishers' websites.
The tokens paid for by the advertisers will then go into the pockets of these publishers, while a small portion will end up with users to compensate them for their attention spent viewing those ads.
It turns out that I might have the concept correct but been slightly incorrect. Instead of being used as the basis for micropayments they will be sold to advertisers who will then use the tokens to buy ads on the platform. Same concept, where you have a bunch of users who "invest" by buying the initial coins and then sell them when the service takes off, but I was wrong about what they're being used for.
So if the Brave platform succeeds then you'll have a whole bunch of people who want to exchange cash for these "Brave Coins" so they can send micropayments. These early investors will hold all the Brave Coins and so they will get the initial influx of cash from people buying Brave Coins to use the platform.
Edit: Possibly the coins are being used by advertisers on the platform, not for micropayments.