I know something. I know that attorneys use contingency arrangements when the client cannot afford to pay a standard fee (often hourly) and the attorneys believe the case is both winnable and 30%-45% of the anticipated damage award will be more than enough to compensate them for putting their time and effort at risk.
Any legal analysis I post is not a formal legal opinion and may not be relied on by anyone for any purpose. If you want legal advice you can rely on, hire a lawyer.