Yes a lot of people make more than $5000 per month, though probably a fairly small percentage of the total number of publishers using Adsense. I don't see the point in your question though.
I know a few people, however it takes quite a bit of work. Personally I like to spread out my income streams.
If you work hard you could make $5K from AdSense even more. BUT, the question is: are u prepared to sacrify (un)expected thing(s) from your life?
It's really a job $5k a month, so they must be constantly looking after/developing many many many sites/proxys/blogs/directories/forums etc.
Many Many Many people make that much. (PS: I don't) Repeat your $50 success 100 times over Agreed. The more you want to earn, the more you have to work for it
patience and work harder! if you can make 50 you're and a good road, and if you're putting your back into it then you'll reach 5000 someday...