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YouTube warns it might make your viewing experience worse if you don't turn off your ad-blocker
(www.businessinsider.com)
This is a most excellent place for technology news and articles.
I shipped several android apps that were GPL licensed and FOSS but had in-app paid options. You could also download a fully unlocked version from f-droid. They were quite profitable and the statistics were surprising. Turns out people are willing to pay for good software