Substance use is the 5th leading cause of homelessness in the USA.
There are more causes that are of way bigger importance such as lack of affordable housing and unemployment which both rank higher in causes.
While substance use is an issue, it should not be looked at as a huge factor of homelessness and there should be more attention to the other top causes
Source- https://nlchp.org/wp-content/uploads/2018/10/Homeless_Stats_Fact_Shee
t.pdf