Paradoxically, as the numbers of gladiators, the frequency of games, and the risks of dying increased, Romans and volunteers began enlisting, until, by the end of the Republic, somewhere around half of all gladiators were volunteers [...] Not only was the volunteer who entered the arena debased, but he was compelled to affirm, to justify, his debasement. He took a frightful oath, the sacramentum gladiatorum: he swore to endure being burned, bound, beaten and slain by the sword [...] The gladiator, by his oath, transforms what had originally been an involuntary act to a voluntary one, and so, at the very moment that he becomes a slave condemned to death, he becomes a free agent and a man with honour to uphold.
Carlin A. Barton "The Sorrows of the Ancient Romans: the Gladiator and the Monster" (1992) pp14-15
For Barton this is one of the psychic torments that characterise the period. Enslaved under an emperor whose service demands sycophantic flattery, humiliation and self-abasement, where might a man find honour?
She adds in a footnote, though, that from the early C1st AD recruitment drives began and even minor offenders were committed to the arena.
Tacitus points to some other sources. Vitellius issued strict orders that:
[2.62] Romans of equestrian rank were not to disgrace themselves by performing in the games and the arena. Previous emperors had driven them to this kind of thing by offering payment or, more often, by the use of force, and a number of Italian towns vied with one another in holding out financial inducements to undesirables among the younger generation.
Cornelius Tacitus "The Histories" trans. Kenneth Wellesley (1995)
What need of ASBOs when you can take your rakehells, wastrels, gangstas, hooligans &c and recycle them as Entertainment?
And - before you mention the Big Brother House - kill them.