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.
The strongest decider in the outcome of the 2016 election is that the Trump campaign spent something like a factor of three more on advertising across the board than the Clinton campaign. Cambridge Analytica was more representative of the notion that the Republicans were willing to spend money on anything that might work than on the efficacy of that specific approach.
At the end of the day, that election came down to a combination of sexism in the voting base (Clinton's gender had a demonstrable effect on turnout among non-voters to vote against her; Americans don't want to admit it but in their hearts they're still pretty sexist) and good old fashioned, well understood rules of how spending on ads can move an election by a percentage point or two. The Democratic party as a whole believed Trump to be so unelectable that they pulled money from the presidential campaign to push it into campaigns down ticket in an attempt to win a massive political coup by controlling the House, Senate, and Presidency at the same time; they underestimated the political position of their opponents and it backfired spectacularly.