biggest issue is the loss of popularity of the respective sport.
what i get from american sports is that NBA, MLB and NHL were a lot more popular but all have lost fans to some extent to the NFL because it operated fairly normal (i know, last year was close, but no games were cancelled) for the last 20 years or so.
the owners and the players risk the popularity of their sport because of 5-10% here and there and thereby risk even higher financial losses.