I peaked in high school. Everyone has those days (or weeks, or months) where they have these thoughts after high school. It's a common occurrence because many people feel like they breeze through high school, without having to put too much work in. Of course you have to study and do the work to get by, but certainly it isn't as much as when you graduate and go to college. College is a lot more work than many students are used to having, and it may feel like your best days of knowledge and work have come and gone. But this is not the case, my friends. This is actually far from the truth.
College is meant to be challenging and it is meant to get you to question the morals and values you have in your life. College is meant to test you and your abilities to stand up to hard work. Just because the standardized tests and easy A's you experienced in high school were easier than this, and your grades were much higher, it doesn't mean that high school was your highest point. There is so much life left for you to live, and you can't judge the rest of your maybe 60 odd years on this earth off of a few challenges you face now. There are so many more opportunities that will present themselves to you. They may not all be as exciting as going out and partying in college, or always having good grades, but these events will still be important to you. It's important to remember that your current situation is not your permanent situation. This may be positive and negative in different aspects of a person's life, but that doesn't mean you should get held up if you aren't getting the results you are used to getting.
People get discouraged by of the workload in college and they think the best work they ever did was in high school because that was where they got the best results. But one bad semester does not mean you are a failure and it does not mean you can't be successful. College is intended to test you and teach you about hard work. But in the end, a potential job will not worry about your C- or D in one class or likely even a few classes in college. It's all about the big picture. College is more for learning and increasing overall knowledge to use in life, rather than just learning the material for a test. Of course the tests are important but a person cannot be defined by a number, especially one taken from a test written by a professor who has a ton of knowledge on one particular subject. This is the tricky part: professors are usually extremely proficient in one or two subjects, which may overlap with some others but apart from that, they stick to what they know. Then they expect students to become near-experts on not one but up to 5 subjects in one semester, all while still balancing everything else that a student may encounter.
There is obviously a lot on the mind of a college student, and it is really hard to balance time in order to have good grades and a social life and a job and maintain your overall well-being. There's a lot of pressure to be perfect and to have everything figured out from the beginning. But I'm here to tell you it's more than acceptable to not have a plan. It's more than understandable to not know where you want to go, and to not be getting the results you're used to. High grades of A's and B's turn into average marks of B's and C's, but that's because college is naturally designed to be more challenging. It's normal to not be at the top of the world and the top ranks of the class anymore once you get to college, and I have news for you: almost no one in college cares about how you were before this. They don't know how your grades were before you got here. And odds are they are in the same or a similar boat as you are. It's hard to put an equal amount of focus on every class, so it's expected that some classes will receive better grades than others.
The important thing to note is to not be so hard on yourself if you aren't getting the results and grades you're always used to getting. You are doing your absolute best, and you are doing a great job. Life is too short to take things like grades too seriously. They won't matter by the time you graduate. Just do your best, and remember that you didn't actually peak in high school-- things are still looking way up for you from here. Don't be afraid to take the leap and learn something simply to know it. Hang in there, I know midterms are happening now and really putting your sanity and stability and knowledge to the test, but you got this! Good luck, and keep up the good work!