How do outsourcing companies make money?

By earning the difference. Entrusting company entrusts outsourcing company to do business. Outsourcing personnel are better at doing things than training new people and consume less resources. Normal companies entrust outsourcing companies to do business, the price is lower than training new people, but the salary of outsourcing personnel working in outsourcing companies is higher, and outsourcing companies earn this difference to make money.