No. The only thing I regret along my career path is being officially diagnosed with a mental illness during a hospitalization, which led me to missing work wit

No. The only thing I regret along my career path is being officially diagnosed with a mental illness during a hospitalization, which led me to missing work without notice, which caused me to become abruptly unemployed (and, eventually, unemployable). And despite the fact that my career ended abruptly and without warning, I regret nothing else. There is no downside to learning new things, even if they don't have immediate application to your life. Even if they never do. Learning is worthwhile for its own sake (at least in my opinion).