Plus people being evicted. In 2019 there were 1600 eviction notices (https://sfrb.org/sites/default/files/Document/Statistics/18-...). If we assume that even just 25% of those are 4-person families, that's bringing us to around 10k a year per homeless/at-risk resident (and that's not even counting those who are at-risk of eviction but did not get evicted thanks to SF's existing eviction prevention resources.
If you use the estimate here (https://sf.curbed.com/2019/11/20/20973811/sf-homeless-count-...) that 18,000 people are homeless at some time in a given year then the figure goes down to 20,000 per homeless.
Also consider that an additional estimated 9,500 each year would be homeless if not for SF's existing supportive housing services (https://sf.curbed.com/2020/3/4/21152501/san-francisco-homele...)
Plus people being evicted. In 2019 there were 1600 eviction notices (https://sfrb.org/sites/default/files/Document/Statistics/18-...). If we assume that even just 25% of those are 4-person families, that's bringing us to around 10k a year per homeless/at-risk resident (and that's not even counting those who are at-risk of eviction but did not get evicted thanks to SF's existing eviction prevention resources.