Hmm possibly, I'm not suggesting that all games grind to a halt as they get more, all I'm saying is that for many games I've followed content has slowed as their income increased.
Milfy City, Corruption, Waifu Academy, Summertime Saga, Superpowered, WVM, Rogue-Like: Evolution, and many more have fallen into this trap.
Then you have the every singe game that is abandoned that still make quite a lot in patreon revenue, that's the worst case scenario in all these cases (though unlikely)
Some exceptions I've witnessed are MITY (although they have slowed down recently), Mr.Dots, KsT, Jikei, Runey and at the very top of professionalism and work ethic is NLT Media.
Finally, there are the devs who've completed their game and continue to reap income but have yet to start a new game (this is similar to the previous examples, I think)