I am not sure what "it" is. Does it refer to First Nations people as a whole or the reserve system? The incidents recited were both in cities but the picture is of the notoriously horrible reserve of Attawapiskat. Only 46 of their 316 housing units are considered adequate and had one day in which 11 people attempted suicide. Attawapiskat does have a near-by diamond mine that pushes a lot of money into the community but which an audit found that their leadership squandered.
On the other hand, the vast majority of reserves I have been to are wealthy due to natural resources, gambling or tourism. The hardest hit reserves are the ones in butt-fuck nowhere with nothing to do but fishing/hunting and getting drunk/high (even though some have attempted to go dry).
There is also the intergenerational effects of the horribly abusive residential boarding school system which psychologically crippled generations of First Nations people and contributed to a culture of abuse and addiction.
So it is not surprising that many of the ambitious young move to urban centres but even then many will have horrible educations, no job skills, experience in the urban environment or a community of support. So many of them fall back to the habits that they have learned, which are not conducive to success.