Shouldn't be a penalty for every day- maybe have it kick in after 5 days of inactivity. People do go on vacation, work, etc.
Some people don't. The criteria being the same for everybody, it doesn't affect 'fairness', but the way I thought it, it will variates peoples scores more rapidly, allowing for more faster gaining of rank and faster losing of it. It works both ways. Also, people who are nowadays in the 100k range already make 3k, 4k, even 10k daily on extreme cases? Losing just 1k per day is very little.