Sorry but Seattle's homeless issues are caused by poor city government and the ideologically skewed policies that are in place. Most homeless people are mostly from outside Seattle, not here. Most live permanently nomadic lifestyles, and many are drug addicts. I don't believe the claim that most homeless in the Seattle area are locals, since every single one I've ever spoken to has told me they are not from Washington. Similarly, when Seattle news crews interview homeless, they always proudly state that they came here from another state because they are welcomed here. The "point in time" survey that claims most homeless in Seattle are from the area is not rigorous because it relies on self-reporting (not verified background data), and local activists/organizations coach the homeless to claim they are long time locals on the survey to solicit sympathy and financial support.
The reason why Seattle attracts permanent nomads and drug addicts is simple. The city simply does not enforce laws and lets them do whatever they want. Even worse, it selectively enforces laws - if you are a law-abiding resident, you will be subject to the law in situations like parking enforcement, littering, environmental laws, and so on. For example, a car cannot be parked in a public parking spot for more than 72 hours and if you or I were to leave a car parked for that long, we'd have a ticket. Littering anywhere carries serious fines. And homeowners have to deal with a draconian set of codes that govern their ability to use property they own and pay property taxes on. But if you are homeless, you can get away with parking RVs permanently in public spots (taking away street parking from actual residents), you can trash up public and private lands, and you can leave needles/feces/trash in wetlands/greenbelts/wherever without consequence. Here's an example of differential enforcement of laws in Seattle, where a construction worker living in an RV was fined while other nearby RVs for "homeless" were not fined: https://mynorthwest.com/1046331/construction-worker-rv-ticke...
No one has a right to live wherever they want, at whatever price point they want, doing whatever job they want (or not working at all), and so on. People have to show personal responsibility for their choices (for example not trying that first hit of heroin), live within their means (instead of expecting to live in a highly-desirable and expensive location), and obey the laws (in support of the social contract). Taxing Seattle or Washington residents to support the lifestyles of those who don't do these things is punishing residents who play by the rules for those who don't. Instead, the city government needs to enforce the law strictly, and create conditions/consequences that disincentivize people from abusing the city's goodwill.