The sentence really doesn't make any sense. "Smart people will stay foolish" is a contradiction (if they're smart they're not foolish). My best guess is that whoever wrote this is trying to say that the "smart" thing to do is to pursue your dreams/goals, even if other people think your dreams are foolish. I suppose "stay hungry" could mean that you continue to be passionate (hungry for knowledge? adventure? success?), or it could mean that you stay poor and don't make any money (because you're pursuing dreams that might not succeed?). But the last part of the sentence really doesn't make sense, because if "waiting for chances" is a waste of time, then obviously waiting for chances is the foolish thing to do. It doesn't make sense to say "stay foolish" by doing something that is not foolish. I don't think the person who wrote this sentence was thinking very clearly.

I agree with Gray. I think it's meaningless.

I think they are attempting to use trendy motivational phrases, but the result is that it sounds like nonsense.

Stay Hungry. Never be satisfied, and always push yourself. Stay Foolish. Do (or be willing to keep trying) the things people say cannot be done. I found this using Google. Stay hungry, stay foolish is a quote by Steve Jobs, which was taken from another book.