There are many reasons why one takes antidepressant, I do yet I love my job and I am happy with my choice.
I take them to manage anxiety caused by my wife metastatic breast cancer (at least it's was only oligometastasis and she had a complete response to treatment that she has to continue as long as the disease doesn't come back) and parkison disease.
Your premise assumes people on antidepressants are not like the GP's wife. We have no reason to assume people are less happy only on antidepressant subscriptions. It could be awareness boosts in mental health, it could be higher stressors because they have more responsibility.
I take them to manage anxiety caused by my wife metastatic breast cancer (at least it's was only oligometastasis and she had a complete response to treatment that she has to continue as long as the disease doesn't come back) and parkison disease.