Use it when someone has no choice but to do something undignified or unwanted due to bad circumstances. After the earthquake, the residents were reduced to living in makeshift tents.
Pro Tip 2/3
Negative Emotion
Implies feelings of sadness or disappointment, often resulting from a significant downgrade in situation or status. An elite athlete, she was reduced to coaching peewee soccer after the injury.
Pro Tip 3/3
Emotional Impact
Can indicate an action that causes a strong emotional reaction like crying or desperation. The relentless criticism reduced him to tears.