I don't see how it's a scam or ponzi scheme. It's completely opt in. You don't put in any money yourself. There is no referral nonsense.

It's just a little token they pay you with should you decide to turn on ads. It's actually a rather interesting cryptocurrency given that it's actually being used for something.

BAT is even traded at Binance. At the height of the cryptocurrency bull market, it was worth almost 2 US dollars.