Yes, certainly. If you want a good real-life version of the Gladiator scene we have Julius Caesar's capture by pirates. These pirates would capture people and sell them as slaves, often to rich Romans.

However, if they happened to catch an important person, such as Caesar, they ransomed them instead of forcing them to work as some agricultural slave (or being forced to fight in the arena!). These important captives were much more valuable being ransomed than simply being sold as a slave. Poor people had no such luck.

Here you can read Plutarch's version of the incident.