Why do people need to be rewarded money to do something like this? Why can't the reward be a better social life or better mental health? As the person says in the article, "Getting away from the smartphone has been freeing, and it has opened my eyes and made me more aware of some of my other bad health habits." That's a pretty good reward for most. I'd take that $100k and use it to spread awareness about social media…
Who says they need to? Plenty of people willingly give up smartphones without direct monetary reward.