Since you mention Android development... I believe there are people who are making a good amount of money with Android apps. However, it may or may not come near what a large financial company pays you.
My basic thoughts are:
1. It will take some time to start generating decent revenues, so be prepared to have patience
2. Many people who work on Android apps report their monthly income on the Internet. You may find such articles very useful
3. If you enjoy teaching, you could teach Android courses on the Internet or in a local college. This will help pay your bills while you are making your apps.
4. Try and be cashflow positive. Even if you are not making a lot of money initially, try and make sure that you do not start eating your savings. This will increase the overall sustainability of your venture. Doing some consulting, teaching on the side can help.