Is it foolish for me to want to take my passions of art and make it into my career in the commercial arts field? I'm only in high school and people keep saying I'm foolish for dreaming so.

I think it's foolish not to follow your dreams if you can realistically pursue it then go for it and don't let anyone tell you otherwise! 

I have a friend that is a wonderful artist. I can't even begin to tell you how fabulous her stuff is - she paints, she creates art for phone cases, the list goes on and on. She got married, pursued a career outside of her art, but kept at what made her happy.

She got divorced, went to design school, got her degree. Had a couple of more jobs outside her field of passion so she could pay rent and eat. Kept doing side jobs for design work. Finally, at long last, she now has a wonderful career in her field.

She kept at it, pursued her dream, had jobs that kept her fed and housed until she reached her goal.

If you have a passion, then couple that with a goal of what that would look like. Keep your eyes on the prize and never give up.