Is reefer a hobby?

[Coleus]

Sometimes, i just wonder why ppl call this hobby because according to wikipedia
"A hobby is an activity or interest that is undertaken for pleasure or relaxation, often in one's spare time."

I know for sure to be success at reefer, you can't just take care of your tank in spare time. Sometimes, I feel like a job though i enjoy doing it.

Relaxation? Are you kidding me? I have more stress than if I don't have a tank..... Coral dying, fish got sick, leaking water, nitrate is high....

Your thoughts? I really don't think this is a hobby. What is it exactly?