Hi Peter. I'm currently preparing for O1 visa. I'm on B1/B2 visa now and planning to extend 2 months so I can stay total 8months while I prepare for O1 visa. My question is if I ever get denied for extending B1/B2, can I have any disadvantages when I apply for O1 visa? I met a person who told me this but I'm not sure whether this is true.

If you're here working on a B1/B2 visa, you're already breaking the law.