The 28 year-old British singer was approached to perform a private gig online to earn the virtual money, reported Contactmusic.
Allen revealed on her twitter account that she turned down to play the concert to the virtual world 'Second Life'.
"About five years ago someone asked me to stream a gig live on second life for hundreds of thousands of bitcoins 'as if' I said. Idiot idiot," Allen wrote on her Twitter page.
The 'hard Out Here' singer regrets missing out on a potentially huge fortune.