You're 100% wrong about this. My mother is a mentally ill drug addict who has been homeless. We forced her into care when it was clear that she could no longer take care of herself. It took help from Adult Protective Services and lots of attempts before they were finally able to make it happen. She would hide from them when they showed up. Finally, she got kicked out of the place she was living and APS saw the conditions and committed her.
What you describe is technically possible, but extremely rare. Even when someone is involuntarily admitted, the stay is typically capped.
Generally, as long as an individual isn't harming other people, "the system" doesn't have a reason to pursue a judgement. Many of these people are isolated from family/support systems or have nobody to actually care or advocate for them.
Further, many of them have complex cases. While treatment may be effective temporarily, it's hard to sustain the level of care after an admission.
