Question about ending [SPOILER!]

So, do you think the doctor really had the condition he was supposed to have?

Or was the doctor pretending to have it even in front of the assistant lady?
- Perhaps to make her be more persuasive on her role, or
- to desensitize her in case someone with the actual condition happen to be a patient, or
- to have an excuse to let off some steam after difficult sessions, or
- just to have some fun (nobody's perfect!)

Also, if the sessions are always free of charge, how the heck is this doctor making a living?

*(I kept the post's language neutral, so even if someone clicked this by mistake, the spoiler would be as small as possible. You don't have to use the same language on your answer)