I have a similar completion rate and for a while I was really gung-ho about doing a Project Euler problem daily. Unfortunately, I discovered that there are sites which purport to have completed all 252(or maybe 253 now) and give out solutions.

That there are people who have cheated their way to high score, completely ruined the enjoyment of the site. It does seem a bit silly, that your own enjoyment of a problem is tarred by someone else's exploits. It shouldn't affect you, but it ultimately does, in some ways that someone else cheating in MMORPG affects one's own rat killing efforts.

That's really impressive. I'd interview anyone who showed such initiative. It's so common to interview "developers" who don't seem like they have any interest or passion about their work.

I think a verifiable history of open source contributions (or an active github repo) show the same sort of passion.

definitely at 30% completion - it shows you are a 'computer scientist' vs 'a person who uses computers in his/her job'