Because only those who lack ambition, drive and motivation will think high school is hard? 

I'm sorry but I can easily counter every single point about high school and show why college is harder and working full time is the hardest. 

You said it's hard to get good grades....not its not. You can easily get at least a C for participating and doing your homework. So if you don't say a word and don't do your homework, that's on you for failing. Writing papers is definitely not hard nowadays since kids use AI to write their papers and cheat. There was no AI when I was in high school and had to cite sources without using sites to do it for you. So sorry, its not hard to get good grades and it's only hard if you're being a lazy ass. 

You said apply knowledge learned outside of class. Yeah that's called homework pal, and yes you need to do it. I work in higher education and i did agree before that homework was a joke. But now, I see why it's assigned. When you only have 16 weeks to teach a lesson plan, it call can't be done in the short time frame you're in class so homework is assigned. Never once have I ever been asked by a teacher, "ok class please write a short essay about why you decided to do this last night or this weekend."

Sports teams do not cut most, to me that's generalizing and also means you're just not athletically gifted. I hate to break it to you, but life is not fair and you don't get what you want just because you tried it. If you want to play a sport, the best players will play, thats how it's always been. You really want to play that sport, then you need to bust your ass at home and the gym to be a better athlete so you can get selected to be on the team. 

Lastly, everything you claim is as I said, lack of motivation and ambition. Things aren't given to you, they're earned. I was a delinquent in high school but I was a starter for football all 4 years, did get good grades (had to if I wanted to play) and still managed to get accepted to a handful of colleges and graduated with my BA. So my honest analysis, you are just lazy 🤷‍♂️