Usage of Brave indirectly helps Chrome become a better product, by significantly increasing stability and security of the chromium-base, sucking up resources that couldve also been spent on a more privacy-friendly browser alternative.
Apple and Google do not share code post-fork, and Apple denies Google ~30% of the browser market, so using "mono-" is wrong. Google has a search monopoly, but not quite a browser and definitely not a browser engine monopoly.
The KHTML/WebKit lineage is more a monoculture in its older parts, but I say this is evolution in action (cf. successful alleles and haplogroups across many populations).
So we are not "contributing" much to any monoculture or monopoly, and the alternative is dying on the wrong hill, as I just posted. Any substantive response?