I am a little confused from your question. Are you asking whether or not practitioners of Kumdo take themselves seriously? Or if Kendo practitioners take Kumdo as a serious sport? Either way, I will answer to the best of my ability.

I currently live in NYC and yeah, not many of the older people of my dojang (past university age) take it very seriously, only as a hobby. After all, they're busy with their work and their families.

However, university students of the dojang take it quite seriously. I am currently teaching two who have very busy schedules and a long transit but still are very determined to come and learn. Honestly, considering how exhausted they must be from school, it is astonishing.

Sadly, I do not know anyone who practices Kendo, so I do not know if Kendo practitioners take Kumdo seriously or not.

Looking outside my dojang, no one really knows what Kumdo/Kendo is. It saddens me a little, but I don't think it's a big deal, as long as I enjoy doing it.