Welcome to the coliseum
The first gladiador matches were a sacred thing at funerals but over the years they changed into a public sport for entertainment and to show power.
Why gladiators Fought
Gladiators in the early years they fought in honer of someone who passed away. In the later years It was a sport and was a thing that the public watched in things know as coliseums. Also some rich people would have gladtors fight for parties and important meetings.
A public sport
This sport became the thing that every one wanted to see. It was like football by the amount of popularity it had. Rome and nearly every city under the romans control had arena to house this event.
Power to the people (in a way)
Gladtioral matches were also used by the emperor to show the people that he could be persuaded and by this I mean people would show a thumbs up for mercy or thumbs down for death and the Emperor is in charge of life or death of a fallen gladtior. In most cases he would choose the most thumbs in oneway or the other.
But the people had no other thing with the government it eventually became a republic where Roman citizens had the right to vote who became a member of the senate.
The gladiators fought for furnarels but it changed in to a sport that was popular for the decades and the emperor took kindly to it.