I don’t want to enter my ssn for Apple Pay but it won’t let people send me money if I don’t how do I get around this

See the following from: Identity verification for Apple Card or Apple Cash - Apple Support

To use all the features of Apple Cash3 you must verify your identity.

and

Apple Cash services are provided by Green Dot Bank, Member FDIC, a regulated financial institution. Green Dot Bank is required by federal law to verify the identity of its customers.

To verify your identity, Green Dot Bank will request Social Security numbers and other personal information to ensure that customers are eligible to use the service.

and

Information that you provide will be sent to Green Dot Bank and their identity verification service provider. Your name and address is securely stored by the partner bank and Apple Payments Inc. If asked, Social Security number, date of birth, answers to questions (e.g. confirm street name you have previously lived on), or a copy of your government ID will be provided to Green Dot Bank and their identity service provider, and stored by Green Dot Bank as long as required by law. This additional information cannot be read by Apple.

Apple created Apple Payments Inc., a wholly owned subsidiary, to protect your privacy by storing and processing information separately from the rest of Apple and in a way that the rest of Apple doesn’t know.