I don't necessarily mean to berate the public, but rather the politicians, who saw that they could use social media/big tech for their own personal gain, and the media, who went along with the narrative that putting all our public communication into privately owned platforms was good for democracy. And maybe our own governments and institutions (speaking from a EU perspective) for dropping the ball in protecting us.
I think Evgeny Morozov's 2010-ish writing was prophetic in this regard.
There are also articles from 2011 where political commenters noted how the Obama campaign broke new ground using targeted Facebook advertisement and outreach, and how EU politicians could learn from it. The many smaller, but in total larger donations given to Obama was contrasted with Hillary Clinton who had larger individual donations but less in total, and the commenters attributed this to the use of Facebook and finding and meeting a younger audience on those online platforms.
People thought that targeted advertisement was a good thing and politicians looked on the techniques from that election and saw the potential for power. It was mostly just those privacy advocates, free software advocates and security experts that expressed doubt and warned about the dangers.