Jep, do game dev now since nearly 6 years in spare time. It take a long time but it is going in the right direction. Your first game will be awesome but the 5th or so is probably the game which will make some money. There are always exceptions to this. But from my experience it takes a long time and dedication.
But never leave your day job unless you have at least 1 or 2 years of funding in advance. As studio you also have to spend some money for software, fees, etc. This is way easier with a day job.
Its hard but if you get to the point where you release your first game it will be great. The 2nd will be even greater. If you see how you will evolve over time will be even more greater :D. Just saying its a lot of fun and pain.
Said the man with ambitious game dev goals, day job with (9+ working hours), wife and 2 children :D.
Life is not a pony ranch.