Savannah Benavidez stopped working at her job as a medical biller in June to take care of her 2-year-old son after his day care shut down. Needing a way to pay her bills, she created an account on OnlyFans — a social media platform where users sell original content to monthly subscribers — and started posting photos of herself nude or in lingerie.Ms. Benavidez, 23, has made $64,000 since July, enough not just to take care of her own bills, but to help family and friends with rent and car payments.“It’s more money than I have ever made in any job,” …