10 million, 1 million, it makes no difference since everyone has a different definition of the word 'user'.

Stop being so abstract, and cut to the chase! Most consumer startups rely on advertising. Let's assume $1 CPM. The most useful stat to care about in that case is 'Average Users Per Day'. So if you have 10,000 average users a day, you're gonna make $10/day and $300/month.

Stop with this users nonsense. It helps noone, ok.. maybe venture funding, since investors love these buzzwords.