Yeah... ok man.
Not sure if this is bait or what but...
If your average grade is a C you need to focus on what is achievable. You can get A*s, but not 16. And it's a ridiculous goal to have anyway. Nobody really cares how many GCSEs you have, much less Oxbridge. If oxbridge really is your aim, I need you to trust me when I say just stick to a normal amount of subjects and get A*s in those - the cost of failure is much, much higher than the reward of success (which is negligible) in this scenario.
Also, the reason that person didn't get into Oxford almost certainly isn't because they didn't do any clubs. It could have been poor interview, admissions test, a-levels, personal statement, or literally anything else that has any impact on uni admissions.
Also, the statement about making decisions and proving them right is makes no sense. You need to have some reasonable chance of success before making important time-consuming decisions. That statement could be used as rationale for literally any goal. "I'm going to jump off this cliff and THEN prove I can fly. Despite having no reason, or past ability, of being able to do so."