Wrong. Read the OPT Policy Guidance, section 7.2.1:

All OPT employment, including post-completion OPT, must be in a job that is related to the student’s degree program. For students who are not on a 17-month extension, this employment may include: (...) Self-employed business owner. A student on OPT may start a business and be self-employed. The student must be able to prove that he or she has the proper business licenses and is actively engaged in a business related to the student’s degree program.