I can’t say to knowing it all, but I’ll do my best to list it down what I know about it. First of all it’s a mix of factors: one of the primary being the climate, since Vancouver has one of the mildest one of the whole Canada; allowing a multitude of people to survive the winter living in tent and on the street.
Then there is to consider the gigantic amount of people using drugs in the city, with some reaching a point where they cannot fully have control over their life in any visible way; considering that there are many “medical points “ in the area, supplying“free legal drugs” as a relief for the most severely addicted, that drove even more substances users to gather there. Plus, the city is notoriously “wealthy” and more “laid back and tolerant” for such kind of phenomenons, making the odds of making money easier than in other part of the country.
I do personally know people that decided to live like that and making “a living” by begging on the curbs: increasing even more the already unspeakable amount of people living on the street. Then There is to add the factor of many mentally troubled people being left on their own after several law changes in the past, and consequently many of them simply gathered in the same areas. Political and economic reasons (as everybody knows the city is one of the priciest market out there, beside being one of the main hotspots for money influx from all over the world) makes their part, as it’s easy to imagine. Some have attempted (or so has been told) to “relocate” people living in that (and many other) area but with little to no results, for the simple fact that moving a person from a to b, simply shift the problem to the new location.
It’s a phenomenon not uncommon in other cities as well: city A send by bus a bunch of people to city B, and city B (not willing, nor being capable of dealing with such a massive issue) simply play the same game, sending everybody back to the starting point. Classical example of dodging the ball, in the futile attempt of making it somebody else issue. These (and I’m sure many other) reasons are what I’ve known for being part of the origin and spreading of this situation. Whatever anybody may think about that, I simply think it’s not a healthy nor logical condition; that said the problem is so spread and massive that I can equally understand how to make everybody agreeing on a univocal solution is not simple. Just hope it will eventually get better: the degradation of the area and the awful conditions those people are living in is astonishing. Just my two bits worth on the topic