I'm really glad that you decided to make this post. Alot of people feel the exact same pressures about the future in high-school so you are not alone. I personally think doing stand up comedy as a job would be really fun!
From a future perspective (I'm now 27) you really can end up anywhere you set your heart to be, and knowing what you want to do for the rest of your life in high-school is really REALLY unusual. The average person changes careers roughly 5-7 times in a lifetime so its likely that the job you choose now is not a forever thing. For me I had no idea whats so ever, it was so confusing for so long but I eventually set my heart on something and now I'm about to become a qualified psych who never completed VCE. What I'm trying to say is that life will always have open doors for you when you are ready and that the decisions you make today, although they can really help you in moving forward, they are not everything.
I think Ggrand makes a fair point about seeing a career advisor as they have the skills and knowledge to help you make a more informed decision. They can explain the types of industry's that are out their and help you to match your skills and interests to studying something that suits. I personally didn't find this helpful for me, and instead found talking to adults in the professions more helpful. Findings out things like how they got to where they are now, what they do, what they wished they knew before, stuff like that..... maybe a particular person such as a comedian could be cool to talk to?
PS. as an older kid and with friends of many older kids we don't really have it all together like you think, and we also have passions and interests that we do outside of work. Work is a big thing that we commit lots and lots of our time to, but that doesn't mean it defines us, and is all we do.
Hope this helps, please let us know what your thinking!