We absolutely are paying the price with our bleeding eyeballs and wasted time trying to read through all that crap. The actual cost depends on how disciplined one can be about their ignore list and not getting down the rabbit troll hole.

The other part of the cost is scaring sane users away with lunatic ramblings. This creates a feedback loop where less sane content encourages more lunatics. I don't know if we can quantify that. It would be nice though if mods could swing that ban hammer more often on obvious shit that I can't link to due to the local rule LOL.