I'm pretty sure that the number of patents you could get revoked with $2.5 billion in legal effort is much smaller than the total number of potentially problematic patents. Unfortunatly fighting bad patents is a classic public good [1] which means its hard to coordinate people on making them.

If your feeling altruistic, however, the EFF is working to help get some particularly egregious examples revoked. [2] I've donated to them and I encourage others to do the same.

[1] http://en.wikipedia.org/wiki/Public_good

[2] https://w2.eff.org/patent/