You determine your success. This is because you decide to make the situation you are in work for you or vice versa. I come across many young people wanting to venture into business but their ideas seem to be all over place. I agree that you need to diversify and spread your risk. However, that only happens once you have set a firm foundation that has proven to be successful.
Applying for jobs on a daily basis including those you are over qualified for, attending every networking cocktail, meeting as many people as you can, knocking on every door looking for opportunities but at the end of the day nothing happens. Why? Many things occupy your mind and prevent you from focusing on that one thing that will open doors for more opportunities.
Focus and channel your energies to one thing. Let it take priority and engage your time and resources in perfecting that one thing. If you have one well thought out idea that you believe will work, then work hard and make it work.
Do the best you can in the one opportunity you have been given so that it can mature and pave way for other opportunities. You determine your success.