Unless I'm misreading you, you appear to be saying "that guy had options I don't have". In my opinion, that's the kind of mentality that causes a person to "marginalize" himself.
I keep telling myself someday...
1. You make your own choices, and there's always tradeoffs. It sounds like you've decided that a busy internship and a high load class schedule are more important to you than working on a startup. Own that decision...you'll own the consequences. If you don't feel it's the right path, change it.
2. Be careful about telling yourself someday...it can easily turn into never. Not saying there's not better times for some things than others, but lean towards taking messy plunges rather than waiting for the stars to align.