I do not expect most shareholders to act ethically. If anything, I think their drive for short-term profit is weakening Google far more than what any 'ethical shareholder' could have done or would have wanted to do.
I was arguing that Google/Alphabet is subject to the same forces that brought down the reign of other dominant companies in the software industry like IBM and Microsoft* . Eventually Google's reign will crumble too, and probably for the same reasons.
Our actions, albeit small can push in that direction, just like small actions helped to bring down others. Choosing other computer providers made IBM unable to extend its practices to minicomputers and left them vulnerable to MS. Linux played a role in denying server marketshare to MS. Popular opinion aided the antitrust cases against both MS and IBM - it is not commonly known these days there was a massive antitrust case against IBM which lasted even longer than the MS case.
* Note that both of these companies still exist and are very wealthy. I for one, do not seek to abolish Google - just to limit their ambitions to something that can coexist with others.