Okay that may be the most important part. At least the "have fun" part. That's what it all comes down to imo. Do what will enable you to have fun, whether that means getting a degree and job that is directly related from the beginning, or perhaps getting a job that isn't exactly related, but gives you the time and flexibility to do what it is that you love.
Second: Is actually a question. How does choice of high school relate to your long-term goals? and what are your choices for high school? I ask because I am unfamiliar with the Polish school system. I have some vague understanding of some non-US systems, but Poland isn't one of them, and I suspect it's different enough anyway that more informations will help! Learning!
Third: I'm not sure anyone but you could determine whether Computer Science or Software Engineering will be a fulfilling path for you. And what you think now could easily change before you ever get to college and get that degree, so yeah. :/
Fourth: As to whether or not those degrees will get you a job in eSports, I direct you to Day's blog. I'd seriously start at Blog 1.0 and read from the beginning. Day goes into the realities of making your life eSports. The tl;dr version, I suppose, is to emphasize the phrasing "making your life" I just typed. Unlike many industries, eSports is a realm where one still does not generally "find" a job. You make your job. You get involved in every conceivable way possible and keep moving forward. You look around, see what skills are needed, hone those skills, rinse, repeat. You find a niche and fill it, and then innovate.
Finally: You're absolutely right. If others can do it, so can you! It will require dedication the likes of which even I can't conceive of, but it's absolutely possible. We have faith in you!