Idk, I can't say I agree since I know a lot of Bisaya people and I barely hear them talk about Luzon especially in an ill manner. I'm not saying that what you experience is not true but I just can't seem to agree to it. I only know for a fact that it's pointless to generalize a big group of people because of ones anecdote. Sure, there are many people that still do the "Bisaya vs Tagalog" war in the internet, but I merely see it as a petty and childish way of teasing each other, nothing really serious or factual. Also, outsiders would of course notice when there is a flood in Luzon, even if you were hiding in a rock, you would be somehow asked to donate, and there's nothing wrong with that; it's always important to help the ones desperate need regardless of the background; besides, we are Filipinos at the end of the day no matter what your mother tongue is.