You guys seem to be forgetting that Ayu is a diva
She requires top notch of every thing (not that this is bad, I'd do it myself) and she has a crew of 50+ people that follow her to her concerts and perform and are both supposed to get paid and have everything covered. (And I'm not just talking about her dancers and stuff, I'm talking about her makeup artists, nail artists, wig fixer, etc etc) -
She also needs to bring her entire rig with her, people who knows how to set that stuff up and rent arenas.
Now imagine this entourage flying all the way to America or Europe for a stadium with 2k people? Not a chance that it won't end up with milions of dollars in loss.