Not even a grown-up book! Read a different magical fantasy book aimed at children or teenagers. And see how good those are, too. Many of them were written before Harry Potter.
I do think HP is good at the pacing and mystery aspect of it. The magical world isn't really that alluring, unless you are a 12 year old kid in 2001 who never read another book until now.
I agree. Many people are imagining, "instead of using his vast wealth to fix the world, he dedicates all his money and mental energy to an elaborate bunker that will ensure his survival in a specific apocalyptic scenario he believes is likely to happen."
It might be more like, "amongst all the random wealthy-person shit he's bought, there are guns and motorcycles (because he thinks they are cool) as well as a pantry full of canned food (because everyone should have an emergency kit and you never know).
But I could be wrong.