As long as you seek happiness, you will never, ever find contentment, as you will forever be chasing the tail of a dragon.
For me, I just one day gave up on the idea that I could ever be happy. I had a long, dark teatime of the soul, but came out of it absolutely content with my lot. Completely changed my life and how I live, and while I wouldn’t say I live in some kind of state of exuberant ecstasy day to day, I am content, and am no longer burdened by the quest for a reified concept.
You can apply marketing methodologies on basically anything and "flood market with it" to the point where it is depleted of any positive impact it might have when used properly.
If you look at people who are flagged as "happiest man in the world", people like Matthieu Ricard[1], you will be very far from the image of someone that reached "some kind of state of exuberant ecstasy day to day".
[1] https://www.matthieuricard.org/en/medias/matthieu-ricard-why...
Healthy long-term relationships, on the other side, seem to require a fair amount of luck, though.
Without high hopes you could just be anticipating things to get worse which tends to lead to anxiety and just a general glum outlook on life. Hoping things will be better tomorrow, but expecting things to get worse is a subtle but important mindset shift.
And I believe that depression in this situation means that You are simply still expecting too much.
It would be amusing if the extra details didn't break down the analogy....
I guess it really is dependent on personality, upbringing and other nurture of the person.
The only way I have seen where this actually succeeds involves believing there is something better than this existence, available on the other side through the deprivation. And at that point, arguably, there is not a lowered expectation, but rather a new, heightened one.