I disagree to certain extent......
This can be a hobby and still be treated seriously......
I take time to read up on niches I find interesting, research keywords, keep up to date with industry news and sales, plan for the long term, improving my definition on what makes a good domain (I think), keep up to date records etc etc etc
I do the above and still look upon this as a hobby, does this mean I am doing the lottery every time I register or buy a name because it is a hobby? NO
When I first started I had this outlook and 90% of those original names have been dropped now, I have started renewing names that I will be happy to keep for the long haul, some will still be dropped after 12 months as you can't get it right all the time.
Dismissing everyone who calls themselves a hobbyist is really not understanding the work that individual puts into their "hobby"
Chess is a hobby for me but I put in hours a week learning openings, end games, tactics and watching games. I take it seriously because I am passionate about it - same as domaning