Why is that? Because most of their revenue is from ads.
How does Brave make money? With ads.
Privacy-centric positioning makes sense to capture a part of the market. But the mis-aligned incentives are there for Brave just as much as they are for Google.
Are they better right now than Google? Probably. Is it smart to trust a company that only makes money with ads with control over your browsing experience in the medium term? Not so much.
It's quite amusing to me how well their marketing works.
What we need is a browser that can exist as a viable business without being chained to ad revenue.