1. Finish high school.
2. Get (and keep) a full-time job once you finish school.
3. Get married before you have children (if you have children).
Their analysis concluded that 97% of millennials in the US who follow this three step sequence are not poor by the time they reach 31 or so.
There isn't anything specific in that sequence about drugs, but I imagine the subgroups for whom drug use would be problematic would also find it hard to follow that sequence while using them.
[1]: https://www.aei.org/wp-content/uploads/2017/06/IFS-Millennia...
It's like saying "we finally found the success sequence for breaking into upper middle class in three easy steps: 1) get a high paying job, 2) get raises every year matching or exceeding inflation , 3) avoid layoffs". Or the good old-fashioned advice for becoming rich: "buy low, sell high".
These are all 100% true, but also 100% useless.
If you're looking for a policy angle, I'd suggest one more conducive to providing more housing and stable incomes.
Even if there was a correlation, why do you assume there is a causation?
But it sounds to me like, for you, the unfettered freedom to use recreational drugs is an inherent good, and that you don't think it should be discouraged even if can be shown to lead to increased homelessness.
The straw person you've now added fills a similar function. You're clearly in search of rhetorical positions that lets you keep repeating yourself without taking the risk of participating in rational discourse.
How common is it that wealthy people become homeless because they recreationally consume wine? Is the prevalence the same as for other groups?