They are very profitable when they win, what is the win rate of class action cases. Also what is the win rate of chosen class action cases versus all potential class action cases.

Measurement matters here.

The 'tipping point' for class actions is usually the class certification, not a final judgement by the court. Class actions are absurdly expensive for defendants, largely due to the scope of discovery, and they also cause problems for public companies (for reporting and other reasons), so public companies almost always settle them after the class is certified. On the other side, these settlements often don't offer much benefit to the class, because the plaintiff counsel take a massive fee off the top, pay off the lead plaintiff, and don't have much incentive to do anything for the remainder of the class.