There's this very insightful post "You Guys Are Millionaires Right?" by Shifty Jelly which I think every indie developers should have a look.
I like this part: "People will spend hours researching a $2 purchase, browsing reviews, emailing the developer, checking online forums. Then they will go to a coffee shop they've never been before and buy a $4 coffee."
Developing mobile application is definitely not an easy task, specially doing it full time. Everyone's different and for me, this is more like a hobby. Unless I can build up certain level of stable income from this, with so many bills to pay plus family to take care of, I certainly can't afford to work on it full time.