> what if the RIAA et al go to ISPs and saying they will pay them to continue monitoring this stuff and if they bring them to court, sue them and win they will give them a cut of the winnings?

This is not a profitable business for anyone but low-level scumbags who are also lawyers (so they do not have to pay for lawyers.)

Related, the music industry loses not a dime to piracy. If all piracy stopped tomorrow, they wouldn't likely make an additional cent. Which means that all money they spend to fight piracy is a loss - which is why they tried to make examples out of people and publicize it i.e. if we will go after this poor single mom, we will certainly go after you. But they would not go after you, because they're not going to spend that kind of money.

Which is the reason for going after ISPs and search engines, to make it their responsibility. Meaning that they would have to pay for the monitoring, they would be cutting off people's internet (which is almost scarier than a copyright violation suit in the age of monopoly and blacklists.) The RIAA could just sit back and spend nothing, just send lists of IPs to ISPs to be cut off, and watch piracy disappear. With the shield of a SCOTUS judgement, ISPs could cut off internet as quickly as youtube bans for DMCA, with no consequences.

The situation now is that they can go after individuals, but nobody is obligated to help. It's all on their dime.