The fights staged between professional gladiators only rarely resulted in death, since these men were far too expensive to kill off. If the investments people put into a gladiator simply ended in a cold corpse on a stretcher, then very quickly gladiatorial fights would become a most unattractive venue for the rich investors (i.e. gladiatorial trainers). So no, the best fighters were almost never killed, at least not in the arena. Also, they were treated very well, much better than the average slave, and were often very popular figures among the masses.

The people who were killed in droves in the arena were most of the time the worst criminals of Roman society, the noxii. They were simply thrown out into the arena without weapons to be cut down by the fully-armed professional gladiators. It was a creative death sentence for them, and one that satisfied the public's desire for real blood.