You are thinking of Crassus. AKA 'the richest man in Rome'.
> https://en.wikipedia.org/wiki/Marcus_Licinius_Crassus
Crassus was a property speculator who also operated a fire brigade. They would assemble at the location of a fire and then let the property burn until the property owner sold the property to Crassus at a bargain price – which got lower every second the fire burned.