It's all about maximizing your income. Great, you earn more in one month than in a year but how much time are you spending on the Adsense sites? If the full time job is preventing you from growing your online income, then yes quit and go for it. If your plan is to sit back and ride the gravy train then don't, because you will go broke.
If I were you, I would max out my 401k which is 18,000 per year allowed by the US federal government and enjoy company paid health care assuming your company provides one. My reason for doing this is because time is money. The more money you can make at a younger age the more time you have for it to grow. I'd rather work my ass off now and work for money so I can enjoy life at a later age while all of my investments work for me. But hey, everyone's plan and priorities is different.