The two cases I’ve met: people who actually are not sure, or they were scared to apply for their dream school for early round; people who just want to say they got into a bunch of Ivies. The thing is, you can’t really wait until your result for early comes out to begin doing your regular apps. Most people would have prepared all their regular decision essays already, so it would have been a waste for them to not apply to some more schools. Also some people do this because of financial aid issues.