Thanks for your response.

I don't know for certain so this is an off the cuff answer, but AFAIK... first of all, as your BAT would be linked to a specified address within Brave to begin with, all created accounts could under-go a strict verification process.

Secondly, the adverts are created locally, not via scripts on the browser, therefore the level of fraud detection is capable of being much higher.

Not only this, due to the ads being more sporadic, and a request to be viewed in a private tab by nature, I'm not sure the feasibility or profitability would be worthwhile to even attempt malicious bot using, I'd imagine the time it'd take to put together and the electricity costs would out-weigh any potential gain if they did manage to somehow crack it.