I'm not sure how you're expecting the answer to this to be anything other than "don't do it". It's clear from the question that you know you're not allowed to do it. We're not the current rights holder, so we can't say whether or not the rights holder would feel aggrieved enough to pursue you through the courts. But free software licences have generally been held to be enforceable when the courts have addressed the issue, and there's no reason to think that CC-BY-NC would be treated differently. Expect an injunction preventing you from distributing your derivative work, at the very least. Some rights holders may go much further, and very substantial damages could be on the table.
My best guess about how it will work out (and it really is just a guess) is that if you do this and your project is not particularly successful, the rights holder will either not know or not care enough to sue you. If for whatever reason your project is immensely successful and you make ten or so million euros out of it, you have just painted a gigantic target on yourself, as you're now well worth sueing. At that point even ambulance-chasers may get involved.
So really, don't do this. It's only worth it if you're setting out to make a commercial failure, and why would you do that?