I think people do care, but they are so busy caring that they can't see if their caring is having adverse effects.
Interesting point.
Anyways, I was asking those questions to see what beliefs you have about others or yourself. A few things determine depression. One is physiological health, and part of this could be deficits in serotonin, but also norepinephrine and dopamine. It really depends on what flavor your depression most has. If you have ruminative or obsessive thinking (and depression increases for many in proportion to how much they ruminate or think over and over again on things) then correcting serotonin can be a godsend; if lack of energy it's norepinephrine (NRIs, norepinephrine reuptake inhibitors); if it's lack of pleasure (anhedonia) it's dopamine (SDRI, selective dopamine reuptake inhibitors).
Most of psychiatry and almost all of psychotherapy and counseling stop there, but there are other health-related aspects that can increase the incidence of depression, such as inadequate thyroid hormone, B vitamins (including B12 and folate, as well as a genetic polymorphism called MTHFR which limits the body's use of these vitamins), sex hormones (one theory as to why depression rates are so much higher in women than men is because of estrogen, which can become too high in relation to progesterone or just too high in general), or adrenal hormones (cortisol especially). The newer stuff is pointing to depression as a (neuro) inflammatory disease, even related to gut health, where a "leaky gut" (intestinal permeability) can cause problems with the gut-brain axis, leading to inflammation and reduction of activity in the frontal lobes.
I hope I'm not boring you. These are real options for treatment.
Anyways, I recommend everyone who has suffered from depression,
especially if it doesn't seem to be related to psychological causes mentioned below, to get bloodwork pulled, such as thyroid (TSH, free T3, free T4, thyroid antibodies, reverse T3, and run screaming from any doc who only pulls TSH, as this is a pituitary hormone and not a thyroid hormone), B12 and folate and if possible a full Nutraeval panel which looks at multiple nutrition-related deficiencies, sex hormones (estrogen, progesterone, sex hormone binding globulin), and adrenal hormones (ACTH, cortisol). For possible inflammation, I recommend anti-inflammatory supplements and diets, as well as addressing gut health, which can be done by cleaning up your diet and taking a good probiotic, and for the inflammation bit taking supplements like fish oil, krill oil, and anything else with EPA and DHA.
For psychological causes, you're looking at beliefs or attitudes you have toward yourself, the world/other people, and your future and past, so if you have one or more negative views (e.g., I'm a failure, nobody cares about me, etc.), you increase the chances of depression. It sounds like you have hurtful feelings that express as anger (anger is almost always a secondary emotion to primary softer emotions like hurt or fear) toward other people, which might mean you have negative beliefs toward others. I don't know, you'd have to answer that in more detail. I will say that a lot of people I've counseled have hurtful feelings and negative beliefs toward other people because on a deeper level they think
they are the ones who are somehow responsible, believing themselves to be defective, worthless, a failure, or abandoned by others.
On top of this, you have mindfulness meditation approaches, which teach you how to defuse from your thoughts (i.e., stop identifying with them or considering them real, as opposed to just thoughts or passing phenomena in your mind), and mindfulness and acceptance for depression is currently the hot approach in psychotherapy and counseling.
I know that's a lot, but it's the best info that's out there for depression. If you're a reader, I recommend checking out Ilardi's book The Depression Cure, Young and Klosko's Reinventing Your Life, and the book by authors whose names I've forgotten, The Mindful Way Through Depression.
There are options out there. A good therapist is always a good one, but I know that can be expensive.