Learn Spanish (Latin America): Ese hombre se quedó pobre muy rápido.

Quedarse is specifically used to express a resulting state after an event, often focusing on what a person is left with (or without). It is very common for losses, such as going blind, bald, or in this case, poor (se quedó pobre). By contrast, hacerse usually implies a deliberate effort (like becoming a doctor), while volverse suggests a deep, often permanent personality change.

Does quedarse always mean a change of state like 'ended up'?

No, its literal and most basic meaning is 'to stay' or 'to remain' (for example, se quedó en casa, meaning 'he stayed at home'). However, when you pair it with an adjective describing a condition like pobre, it transforms into a verb of change.

What happens if I drop the se and just say quedó pobre?

To express a change of state, you must use the pronominal form quedarse, which requires the pronoun se. If you drop the se, the base verb quedar usually means 'to be located' or 'to have left over', which wouldn't make sense in this sentence.

Can I use rápidamente instead of rápido here?