From an interview with an old therapist:

PN: What was it about being a therapist that you loved so much?

POLSTER: I loved being engaged. I loved mattering. I loved digging deeper into the specifics of the moment. I liked the sense of being myself and also feeling like a member of the wider human community.

https://www.psychotherapynetworker.o..._noonthrottled

The part I found interesting was that at least this one did not try and couch it in how much he cared/was a healer/etc. He focused on himself and not how altruistic he thought he was by becoming a therapist.