He probably wasn't making enough money to keep it going. Especially since few were donating I'm guessing. And even the tip amount was ltd then €1. That's too low.
This way he gets some money for all his hard work. But it's crap for everyone else.
I find his apps too simple and the dialer had a bug where if you get a call and accidently swipe away the notification, the phone would ring with no way to answer it.
Actually the dev said that he didn’t like the direction android was going in so he wanted to quit development. Nothing to do with lack of funding at all
The problem is that the dude started out claiming it was a project for his own satisfaction. Then he tried to monetize later, and now wants to cash out.
Which is fine, that's the way the world works. But the number of developers that make one claim or another and then change their tune later is absurd. It isn't even about the money aspect, it's that the dude switched gears rather than making a realistic plan from the beginning.