That's where all the details come into play.
What you're doing for a living.
What you're getting out of it.
Your financial situation.
Your financial habits.
Etc.
All of the above doesn't make a difference at all.
Whatever your financial situation/habit is, if you could've made more money by running a legitimate business during the time you spend on DDF, you're doing something wrong.
As for the question of how much time you spend on DDF, well, everyone who's IN the game spends a LOT of time.
Most of us, myself included are not even aware how much time it is.