Not sure. The "undefeated for 2 years" badge also meant that whoever did it first had serious boasting rights. Might end up being worth more than the 60k prize.
Saying the prize is 1M (it isn't!) is just eating the marketing.
Though I find these contests very interesting, I can only wish that as much resources was spent to develop a viable alternative to C++ that would make many of those vulnerabilities impossible. Languages like Rust, ATS and BitC come to mind.
gnuvince may be referring to C++'s lack of automatic bounds checking, which can contribute to exploits via buffer overflows. (But I am neither a security researcher nor a particularly competent C++ programmer, so I may just be completely off-base!)