Which people adopting Redis didn't had to pay for, if they had to, they would rather suffer with those other less capable open source alternatives instead.
It wasn't a "demo" for a paid product funded by corporate dollars or VC funding, it was just a thing that someone created, and released as an open source project.
It's hilarious that you think the companies dropping open source licenses for the products they bought are going to stop the industry using open source. As I said originally, it's going to have the opposite affect: it's going to make the industry embrace the very nature of open source and create forks of projects, the moment there's a sniff of a corporate buy out, specifically because of this type of activity.
The ongoing uptake in open core, shows where it goes.
I find it hard to believe many if any would see "create an open source tool" as a method to become a millionaire.