Environment defines genetics. Genetics define the individual biologically. This biology interacts with the environment. This interaction between biology and environment leads to the development of intellect as a process of learning and retention of experiences, which is influenced by environmental conditions as base as types and quality of foods available all the way through the gamut of things which you could consider "learned" behaviors. These learned behaviors are passed on, modified, this is how culture is built up. Culture then begins to feed back into this interaction, altering it as well. Over many generations and thousands of years these behavior exchanges and environmental interactions/biological reactions to external stimuli are compounded and become more complex, more abstract as intelligence and (more importantly) free time to consider the abstract increase.
To ignore any facet in these interactions is to ignore the whole, yet Dumar ignores entirely the biochemical and physiological aspects as well as the "environmental" aspects in regards to physical environment rather than cultural, in the process he focuses entirely upon cultural impacts and blows them up and distorts them as the sum total and cause of all human ills.
Never minding the fact that modern society was an attempt to move out of a world of constant and unending human ills and pain and suffering of unimaginable proportions, he rails against it because part of the cost of that cultural evolution was the commodification of materialism, which he sources as the font of all wickedness in our world.
Right, the idea that sociology could ever justify suicide for base reasons like "Life is hard because people suck" is nonsense. Suicide because you have a terminal disease is a lot different from suicide because depression.
The fact that suicide causes immense harm to everyone who is related to that person in some way is enough for sociologists and anthropologists who adhere to a doctrine of primum non nocere to know to back away right off the bat. Suicide for reasons subjective to one's perception of the fairness or unfairness of life is not, and never will be, justifiable just because mean people suck, which is really the crux of Dumar's greater overall point.
For one thing, no reasonable, logical person should be allowing the actions of others to dictate their own life's course so completely as to consider death a justified reaction to what amounts to being bullied.