Most .io sales are tech related names, absolute premium keywords or brands that are very synonymous with the tech world, matrix.io and tank.io come to mind. I am sure names like monkey.io, tomato.io will all do well too in the future, but that is because they can be branded for tech purposes.
I can't see how addiction.io fits into the above though. With a keyword like addiction I would expect to see .org or .com after the name, not .io.
In my opinion I feel you have overpaid for this domain name at $800. I hope I am wrong and I wish you all the best.