In 2001, I built viral personality tests that for a while were the most shared content online. In 2016, this same mechanism was used as a backdoor to democracy.
I wrote a piece over on Medium about how Cambridge Analytica created psychographic profiles for 50 million users:
Elections have become information warfare battlegrounds, fought using all of our personal details without our consent. Here, the weapons are vast data silos like Facebook and Twitter, alongside open, anonymous marketplaces for highly targeted advertising.