I've been to most stadiums in Germany, few were as empty as the BayArena. And of course Bayern has tons of success/Event Fans. The same was true for Dortmund in 2011-13. Success sadly attracts people who might otherwise not be interested as much and there's not much you can do about it. Maybe the current success will actually fill your stadium for a while.

Let him live in his own world. It just shows how little knowledge they have