If the big guns in charge of Amazon/Google decide that Trump (for instance - only using for instances - nothing legally liable!) should be voted in as president, then can you not see that they can influence people through targetted ads.
Ah, do people not know Facebook ALREADY did this?
Facebook embedded employees in the 2016 Trump campaign, actually sitting in the Trump campaign offices. They helped micro-target ads so that individual voters would see the stuff that appealed to them in particular, and not the stuff that would turn them off.
Interview with one of Trump's campaign staff:
The digital guru who helped Donald Trump to the presidency
www.bbc.co.uk/news/av/magazine-40852227/the-digital-guru-who-helped-donald-trump-to-the-presidency
(Clip is 4:41 mins; go to approx 1:45 min onwards if you're short of time.)
As far as I know, Facebook did it because they were paid lots of money for doing it. I don't know whether there was also any idealogical support – and if so, from whom within the company.
In a sense, it doesn't matter that it was the Trump campaign. This will now be used in the future for all politics.
There may be a difference between just how low and unscrupulous different campaigns will be prepared to go. The essence of micro-targeting is that a campaign can show, eg, a racist advert to people it thinks will respond well to racism, while keeping the same advert invisible to people who'll be repelled by the racism, and also keep that ad under the radar of the news media.
This is the sort of thing your boring, day-to-day data is being used for.