Consider some moderately busy traffic signal in chennai. It throws a red-signal approximately once in 5 minutes. On an average, say we have 10 red-signals in an hour. A begger manages to collect atleast Rs.5 in one such red-signal. So, in an hour he/she makes Rs.50. If the begger works for 10 hours a day, he/she makes Rs.500 in a day. Supposing this begger works for 5 days a week, then he/she makes Rs.2500 a week. Which is Rs.10000 in a month.
An enterprising begger could have some kind of a piggy-bank to collect all money for a month so that he/she gets the monthly amount as a one-time pay cheque.
No wonder we have so many beggers in the city.
Edit 1: Remember that these guys dont pay tax. Nor are they included in the calculation of average Indian income (which is way way less than Rs.10000).