I think it's important to figure out if you are going to be together long term before you determine how to support him. You have a 1 1/2 year old child but you aren't married. My guess is you'd be a little less worried about this if you were married. A husband and wife working as a team to make a dream come true often brings people (closer) together.
However whether you are married or not (no man wants to be stuck with a "dream killer"). If you don't support him in his business venture he will not be around you much longer. No matter what, "life is a personal journey" and each of us are responsible for our own happiness. One has to pursue their dreams in order to avoid dying with regret. Hopefully your boyfriend would be supportive of your dreams as well. The best thing you can do is let him know you back him 100%.