The homeless population (including those in shelters and cars) is < 1% of SF's population. Even if they used products at the same rate as the rest of the population and stole 100% of what they used, they would be responsible for less than half of retail shrinkage.
Of course they are stealing things for their own consumption. They are merely choosing to steal a particular thing that is easy to steal and easy to convert to cash, which they can then use to purchase the diverse things they need to survive.
