1) Sarcasm is not argument.
Your ability to understand an idea well enough to re-state it sarcastically is the intellectual equivalent of training wheels on a tricycle. Friends that put up with you despite this misunderstanding will turn out to be real friends. If a professor ever relies on sarcasm to discredit an idea, their own ideas are probably weak.
2) You have no idea.
Changing your mind based on new information is a mark of progress, not weakness. The current perceived authority figures in your life are not the exclusive distributors of gospel truth. Approach people with a baseline of respect and approach their ideas with a baseline of skepticism. You're not in college to learn life's answer key. You're in college to learn good habits for a lifetime of future learning. Retain what proves itself to be useful, leave the rest behind. There's no reason to take on other people's thought baggage, you'll have plenty of your own soon enough. Whatever you're thinking right now... be prepared to change your mind about it.
3) Easy isn't easy.
Take any discipline. Anything. And research it. You'll find ever expanding layers complexity. You'll find people who have spent their lifetimes working out aspects of design, engineering, philosophy within that discipline that you don't even know exist. Everything in your life that's easy is only easy because someone else worked really hard to figured out concise ways to solve complex problems and then provide those solutions to you in a form you can comprehend. Understanding a concept is not the same thing as solving a problem. All else being equal, prefer advice from problem solvers over concept regurgitators. Their opinions do not have equal weight.