A FACT is that Ryanair carried 60m passengers last year
I am not sure what the no show rate is but when people buy seats for just a few euros the it is likely many will not show. Some people are in effect buying an option to fly. If you are not sure when you are going then some will just book a few flights and just turn up for one. I suspect they carried around 55m passengers last year. The thing that counts is how much income you make.