You don't have to participate in the advertising bits of Brave; those are optional. But, they're a privacy-centric way to generate rewards which can be passively contributed to your favorite sites, sustaining their content creation.
I would love to hear more about your privacy concerns; we have excised quite a bit from Chromium. You can read about those changes [on GitHub](https://github.com/brave/brave-browser/wiki/Deviations-from-...). We also audit our network activity to make sure nothing ever slips out. You can read about our [desktop](https://brave.com/brave-tops-browser-first-run-network-traff...) and [iOS](https://brave.com/ios-browser-first-run/) audits on our blog.
Perhaps more of interest would be an independent, third-party review and comparison. Trinity College's School of Computer Science and Statistics did a comparative review of Chrome, Brave, Edge, Firefox, Yandex, and Safari. They found that Brave was the "most private" in terms of phoning home. You can [read their review online](https://www.scss.tcd.ie/Doug.Leith/pubs/browser_privacy.pdf).
Always happy to discuss any specific concerns you may have.