1. Apps are generally made by wealthy, well-off people.
2. For many apps, the goal is to create an experience that satiates the addictive urges of people with poor impulse control. These people often turn out to be less well-off, possibly because they have poor impulse control.
3. Because money is going from the less-well-off to the well-off, wealth is being redistributed.
There's not a whole lot of research on these people, but I don't know of any evidence that they tend to be poor, while there is definitely anecdotal evidence some of them are extremely well-off ($200k+ salaries [1]).
[1]: http://www.polygon.com/2012/11/1/3587102/high-rolling-whales...
I do wonder about the thinking of people who make games like this. I mean when the business model is about getting your customers literally addicted and there's no benefit besides "it's fun" (questionably), I don't see how it's particularly different from designing slot machines. I did find a blog that discusses that perspective in more detail: https://drmarkgriffiths.wordpress.com/tag/slot-machine-addic...
Team Fortress 2 is often described as IAP done right - purely cosmetic items that confer no gameplay advantage. So it's useful to see that even that can exploit vulnerable people.
Should game makes pit protective measures in place? Or at least have a process that allows players to self-report their vulnerability?