The thing many don't realize is that all dates are sold out. But many of those people are impulsive buyers who don't even know what Big Time Rush is. The more media attention they receive. The more people will look into it.
Honestly
I think what they messed up with the Big time rush sale was that there were like 3 pre-sales before the general sale for a venue that's way too small
Maybe they thought the tickets won't sell but it's still fucked up