That would be prohibitively expensive. The number of overly broad patents that patent trolls own is way too large to be able to challenge them in a cost effect

That would be prohibitively expensive. The number of overly broad patents that patent trolls own is way too large to be able to challenge them in a cost effective way. If you want to play offense rather than defense, your money is better spent lobbying to get the law changed so that overly broad patents are more difficult to acquire in the first place.