I mentionned Berlin Fang, a literary translator I met at Annaghmakerrig last year? We had great conversations about the job of translator and recently Berlin wrote a post on chinadaily.com about just that. For a fascinating (and inspiring, and comforting!) answer to the question of this post's title, just click.
You will find out why we shouldn't do it:
"At present, most publishers pay about 65-100 yuan ($10-15) per thousand words for literary translation, no matter how good you are. You know that words are cheap because the rate has remained at this level for decades. The rate is so pathetic that I once considered giving up translation in pursuit of a career as a pig farmer."
... and why we do it anyway:
"It's my secret dream that one day or one night, a Chinese author reads a book I have translated and bangs on the desk: "I didn't know that novels can be written like this! I can do that!" There, the circle of life for writers goes on."