this is a well known secret with cast members, many cast members supplement their Disney wages by being unofficial tour guides or selling their freinds and family free passes.
Some things to be aware of
1. Park CM wages are mainly minimum wage and not tipping positions. Depending on the hours in the park CM contract, their wages are often not enough to cover rent or other living expenses. Many Disney CM's will also work in Universal for example
2. Disney takes a very strict view on CM's being unofficial tour guides and selling their free passes. If a CM is reported or caught, it is very likely they will loose their job.
3. If you do report this CM are you comfortable with knowing that they have lost their job at Disney and may not be able to pay their rent, or have food etc.
Also bare in mind, that Disney has other employee benefits such as healthcare. It may be possible that this CM is relying on Disney healthcare to cover medical needs and expenses.
4. These things are not always black and white. Just because YOU are a good employer and look after your employees does not mean that every workplace is like yours. Reporting a CM may have extremely harmful consequences.