Gladiators were usually recruited from criminals, prisoners of war and had no choice in becoming a gladiator. There were some, free born men that lost the right of citizenship but still decided to bind themselves and swear their body and soul to a troupe.
Their oath was "To endure flogging of the sword, branding, chains, and whatever the master ordered." Half of the gladiators became volunteers by the end of the Republic.
Even though a man lost his social standing and was treated as a slave there was an honor to be felt that he belonged to a group, noted for their courage, and discipline. Other social and economic reasons were taken in consideration, the opportunity to only fight several times a year, and to have the recognition and opportunities let alone they were the adoration of females.
It was rare in the beginning but females began to fight as gladiators, sometimes on chariots or with dwarves. This was beginning to be so popular, Septimius Severus (late second, early 3rd cent. AD) banned female gladiators.
Emperors, some mentally unbalanced, were placed in the arena with knowingly weakened soldiers so they would win. Later other emperors of sound mind such Titus and Hadrian either practiced as gladiators or fought in gladiatorial contests. The training of the gladiators was taken over by the emperor and was owned by the lanista to be trained. The lanista either rented or sold the troupe and it became a very lucrative business, frowned upon by the Roman people.
The amphitheater or the widely known Coliseum, had special socialized seating, a separate box for the emperor and his family, senators and knights had there own sections. Soldiers were separated from civilians and married from single, as well as women seated with the poor unless they were Vestal Virgins who sat in the best seats with religious officials.
Clothing worn by men was usually a tunic and women wore togas of fine silks and they dyed their hair in many different colors usually adorning it in curls and wearing sandals on their feet.