I agree with your intuition. The likelihood that the person actually hates saving money is approximately zero. What they are actually saying is that you haven't earned their trust enough yet to cough up their email address. So when you force the question with a timed modal, they have three options: sending their email address to a site they don't trust, clicking a link that's simply a lie or just closing the tab and never coming back. Why on earth would they pick anything but the last option?