system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is therapy effective when it is in the therapists' financial interest to keep you as their patient?

Same goes to other medical fields, I guess. 

How can a doctor make you better when their job requires people to be sick?
gpt
Aside from the personality types looking to get into these fields of work there's two objective factors that would make it a bad idea to prolong treatment and they kinda go hand in hand: supply and competition.

Many therapists have lines of patients waiting to get appointments and if you have a bad reputation they will go somewhere else.
This is also the case in countries with free healthcare, but there you also have the added reason of costs.