"Required by law" as not as powerful as it sounds.

Law is not powerful enough to protect someone from a violent partner. Restraining orders don't stop violence from taking place. They only promise punishment afterwards.

So you do not pursue a violent partner for child support, even with the law on your side. It is too dangerous.

Online sex work is the safer option.

Oh, also, you seem to have the idea that child support money is enough by itself for the costs of raising a child decently. It often isn't, you need another income source to cover it. In the example we are talking about, the person could not do a typical job, so they had to find an alternative and OF provided it.