Ah, I didn't realize you were recommending doing that. Hmmm...
I only have one experience doing this, but from that, I have to disagree. To book your own concert legally, you need insurance for the night, etc, and the costs really add up. My old band did this for a New Years Eve gig a few years ago. We had a large following, and got over 100 people to come to the show...but, when all was said and done, we ended up paying a little bit for the night. Yup, we lost money. When you rent a hall, there is the rental fee, the price of advertising, the additional price of restrooms/trash removal (most halls have this fee separate from the rental fee), the price of the insurance (I forget the number, our manager handled it, but this was by far and away the most expensive part of it all, way more than the hall), the price of any food/drinks (you can't serve booze, obviously), etc.
I can honestly say that, when we did it, it was the worst experience I've ever had in a band (doing all the prep stuff), even though the show was a blast.
Besides, like I said, pricing varies...we make $400 - $600 at some of these places. To make that, after expenses, if you booked your own show, you'd have to have a couple hundred people show up, or have really expensive tickets.
Again, I only have the one experience...but it was a nightmare.