It depends on the period. Republican era gladiators, at least before Spartacus' revolt, were not viewed as especially valuable because slaves were so common, primarily prisoners of war. After Spartacus, more effort was made in training and practises introduced to prevent them becoming a threat, such as keeping speakers of the same language (other than latin) apart.
Principate era gladiators were the professionals we normally think of. Note the photograph above. Neither conforms to an established class and are dressed incorrectly. No gladiator wore a breastplate - the chest was left bare as the major vulnerable area (thus a quick thrust ended the fight in a clean manner). Nor did gladiators wear tunics or robes under their equipment, for various reasons, including the possibility that bladders could be hidden and a false result concluded. Neither gladiator has a padded right arm (this was to protect the fighter from bruising himself on his own shield, the same reason for padding the left leg)
Dominate era gladiators suffered from a change in emphasis. Gone were the days when the crowd thrilled at the sight of a real swordfight. Now they wanted more theatre, thus more exotic weapons designed to wound rather than kill were introduced, leading to fights where it was down to who had the best endurance against wounding as much as fitness. But then, these were also the days when gladiatorial combat was increasingly looked down upon. Septimius Seversus had already banned female gladiators, and in 393 theodosius banned pagan rituals (which was what the gladiator fights were about in theory at least) whilst in 404 Honorius banned them outright - though fights in remote areas persisted where christians weren't able to stop them.
Value depended on success. A tiro gladiator had roughly a one third chance of dying in his first fight, and good chance of being paired with a veteran fighter. Eventually, with survival and experience, a gladiator could reach survival chances of about 8 in 9. Only a small proportion of human beings are natural fighters and this was reflected in the survival rates.
Typically a volunteer could expect to sign on for five years. Shorter or longer contracts existed, but five was the norm. It was also usual for a gladiator who survived four years (the life expectancy of a gladiator incidentially) to be set aside as a Doctores, a trainer, such as the character Marcellus in the Kirk Douglas film Spartacus.
Gladiators were owned as troupes either by lanistas or private individuals (Cicero praises his friend Attalus in a letter for his excellent troupe of fighters). When fighters for games were required, a contract would be arranged between the games organiser and the owner. It was usual for compensation at fifty times the rental price for a fighters death. In other words, the games editor had to weigh carefully which was preferable when the crowd booed a contestant who could not continue - to please the crowd, or avoid a massive bill. Some gladiators were owned as bodyguards, some by military officers who used them to train soldiers in fighting tricks - laughable when you read how useless gladiators were in battle.
The gladiator was allowed to keep a proportion of the prize money. This was how gladiators got wealthy if they survived. In fact, the potential money was the biggest draw for volunteers, though some clearly dreamt of super stardom in the arena. It was possible for a gladiator to buy his freedom though in truth I haven't seen much evidence for that. In fact, it was noted that gladiators formed strong ideas about performance and pleasing their owners. Although the troupe was a familia, men fought their best friends if need be. there's an inscription on one funerary monument that a man should be careful who he spares - since although a fighter could spare an opponent, refusing an order to kill him was rebellion and the normal practice was to bring in a fresh opponent until the refuser lost.
Fights to the death? Well, they did happen, because Augustus banned fights sine missione (without mercy) but these weren't the norm. A fight was supposed to continue until one or the other could not manage any more, either by exhaustion or wounds, and a decision was made on his fate. Missio, the honourable release of a loser, was quite common - costs being what they were. Obviously swordfighting was dangerous and hence a man could be killed outright. Demo fights in the morning would end at the first blood, professional bouts in the afternoon were serious, with rest periods if the match went on a long time (this practice tended to vanish in the Dominate where exhaustion was part of the drama).
On the other hand, we have Seneca visiting the arena one lunchtime and he was horrified at the spectacle of death. Hoping to see some entertainment, he reports that "It was sheer murder out there". So sometimes, orderly contests went by the board.