If you are getting enough revenue then its not matter, when you going to sale it, good alexa site only can be sold in good price.
i personally dont find any real value to alexa. what i worry about is google and yahoo since thats where a lot of my visitors come from.
I have never taken care of Alexa ranking while I do SEO of any website.. May be I don't know about its importance as I am not having a more experience in this field..