Ever been through an acquisition where 50% of the team was to be let go and you had to decide who and then tell them? Kill off a product after the team had almost completed it? Perform a lay off when times got bad? Give a serious, reasoned, estimated answer to the question (from the CEO): "How fast could we rewrite our entire code base from $FOO to Java?" Fire someone 20 years older than you and wonder quietly to yourself if he'd find another job? Manage more than a handful of engineers? Figure out how to outsource part of your development to India for financial reasons? Deal with a rapidly expanding customer base with creaking code? Manage a multi-million dollar budget when VCs aren't throwing money at you? Handle alleged sexual harassment? Spend hours and hours flying from customer to customer to explain your technology?
The 'pick which technology' to use part is easy and fun. Now go make that work in a real environment with real constraints.
My advice on becoming a CTO: learn how to write. You'll be spending a very large amount of time communicating your ideas.