I just can't make it the rational behind not paying to their writers. They take a lion share without even reading the description of the paper and the writers get paltry sum after laboring for hours to meet the requirements.
If they keep on losing their writers, one day there will be none, who will write the papers then?
In an Oriental proverb, they say: "if one burns her lips drinking the hot tea, she'll never gulp at the cold drink".
There are some other sites offering the same gain, I just fear it wouldn't be the same again.