Personalised ads are beside the point. The issue is how they are personalised, namely by building a rich profile of user behaviour based on non-consensual tracking.
It isnt even clear that there's a meaningful sense of 'consent' to what modern ad companies (ie., google, facebook, amazon, increasingly microsoft, etc.) do. There is both an individual harm, but a massive collective arm, to the infrastructure of behavioural tracking that has been built by these companies.
This infrastructure should be, largely, illegal. The technology to end any form of privacy is presently deployed only for ads, but should not be deployed anywhere at all.
Using it to sell you shampoo isn’t terrible (it can be super annoying though). The problem is using that data to eg figure out who might be in the market for pregnancy related products. Or, ominously, who have stopped buying pregnancy related products early.
Or correlating interest in something they browse with voting intentions. Or interest in political action. There’s a lot of dodgy things you can do with that data. And little of this is being shared with *informed consent*.
Ads are NOT the problem. I love browsing through ads in magazines I buy. If online ads worked like outdoor ads or magazine ads, I suspect a lot less people would have a problem.