Let's consider these three statements:
1. I want to make art - The combination of technology and low barriers to entry has made the ability to create art more accessible to everyone. That includes you.
2. I want to make some money from my art - I believe that this is a challenging, but achievable goal. Will you make enough that you can quit your day job? Probably not. But I think it's possible to mix in your artistic passions with your "real life" in a way that generates real revenue.
3. I want to make a full time living from my art - Notice that in Point 2, I mentioned real revenue. To make a full time living you need real, consistent, revenue. It's the consistent part that makes a full time living such a challenge. A part of being a freelancer (and if you're an artist, you're a freelancer) is that the money swings. You have good months, great months and then long (sometimes REAL LONG) stretches where nothing comes in.
Being able to make a full time living means that you must have the stomach to handle the swings. A lot of people don't. There is no shame in that, it just means you have to be honest about your own ability to handle uncertainty.
You should also understand that your ability to handle the swings will change over time. I just turned 36. My life has given me an ability to deal with uncertainty, but I also know that I could handle it a lot easier when I was 26.
If you can't handle the swings, stick to options 1 or 2. Your life will be much easier.