If you want to make a living developing- don't do what everyone else is doing. It's the same for starting a business, if there are 13 doughnut shops in your town, maybe you should consider starting a business that isn't a doughnut shop.. (the microtransaction bit is stale, I haven't spent money on a microtransaction in 4 years, have you?)
Find a niche, look for unfulfilled needs, do something to create a product (not to make money).
There are many many unfilled niches- you're more likely to make a living if you specialize, and focus on something that people require, but don't have. Games are great, and if you want to make games do something spectacular because you want to make a great game, once you have the game completed
invest your money in marketing because you have a product that you can sell. A lot of developers trying to break into the mobile market do things backwards- you should make a good product, then attract customers.
If you want to quit your day job to do mobile development, but you aren't able to develop alongside your current work schedule, you will have a very hard time completing an app while not working. You'll be worried about your dwindling funds, you'll be worried about potentially failing, you'll have concerns about your bills, programming is an artistic process- and the more pressure you put on yourself the more your performance will suffer. If you want to start a business, do it, get it working, then