Rich people who want custom homes often want to design it themselves, and then get extremely annoyed when confronted with the reality of basic design principles, usability, materials, structural integrity, etc. And then like to change their plans last minute once they actually start to see it framed in (assuming they don't freak out because they've never seen framing before and don't realize it isn't done yet). Or perhaps one of their rich friends made a glib comment or a jab while being shown the foundation and now the customer wants both their kids to have their own recital hall, because one isn't enough.
Another stellar example: someone wanted a garage put above their kitchen because they wanted to park their ferrari next to their bedroom on the second floor. Damn the exhaust fumes.