My wife is a piano teacher. This describes a large part of her job, especially since she focuses on beginners. She'd be so happy if she could teach "Moonlight Sonata" all day. "Old Macdonald" is much more common.
My wife does feel looked-down-upon by some in her profession who see teaching advanced students as more prestigious. But the process of taking a student from beginner to Beethoven (not that she stops there with her students) is every bit as challenging as taking a student from Beethoven to Rachmaninoff.
My wife is a middle school mathematics teacher (and a damn good one). Sooooo many former students (now high schoolers) have approached her and said, "Because of you, I excelled in math in high school...and I love it!"
She had a student last year who actually told her in a very long letter, "You taught me that math matters. You taught me that I MATTER."
The earliest teachers / coaches / mentors set the foundation which is absolutely critical for all future learning.
Want to experience the highest of highs? Become a teacher. Alas, being do close to kids who are changing so rapidly (and often struggling with things outside of school) it also comes with some pretty deep lows.