If you want to make money it's going to depend on a few factors.
1) Are you willing to hustle hard. Those people who say they are making $2k a week are probably putting in 50 plus hours a week.
2) You need to be in a well populated area that has lots of disposable income. Plus, the people using TaskRabbit are educated and see the value in outsourcing.
3) Those 3 people interviewed are considered the elites of TaskRabbit. 2 live in San Francisco and 1 lives in NYC. The cost of living in those cities is extremely high. A $100k a year salary is like minimum wage in other areas of America.
So, it depends. I live in an area where few people would use TaskRabbit. Many middle class people are struggling with their own bills. The people who would benefit from this service are going to be the upper middle to the rich. It could work well. You just need to be in the right place and you must be willing to hustle.