Based on the post, he was on his 4th year, and his current number of monthly paid subscriber was 810 for 4$ a month (thus less than 40k$ a year)...

I got a feeling that he just didn't see an opening toward making this viable against YNAB. An important fact is that YNAB increased their pricing recently, which caused quite a bit of stir up and an exodus to competitors. Everything was in his favor, cheaper than YNAB, people were freely advertising his app. As he mentioned he started to try to implement Plaid, I guess he did the math and found out that he would get too close to YNAB price (for sure it's going to be a few dollars a month)...