Your rep points has nothing directly to do with what you give, only what you receive (indirectly giving helps, if you get reps in return, since then the people giving to you will have more to give).
The total undoubtedly draws from the MTF join date. Back when the system was started, I doubt anyone thought about maximum values. In fact, I know from asking a veteran that back then the dots were even in play - not as now, when most newcomers go straight from one to ten green dots on their first rep. But it turned out that after a few years points accumulated and became big numbers indeed.
Cheers. Also bemused by the fact that there are 11
green dots by avatars with everyone (that isn't entirely useless) having 5 dark green, 6 light green. Nice, and er... round.