...the Bestiarius was the most-despised of the lot ...QUOTE]
Usually a criminal, untrained, low investment and therefore dispensable.
Good way to deal with those who rape and murder. Let them face up to something that fights back and has a better chance of winning.
Seriously though, what awful times they must have been. Absolutely no mercy for those who transgressed or, more unfortunately, fell into hard times from a high position in society. Quite a lot of men in Rome sold themselves as gladiators to clear their debts.
Some gladiators were so good and beloved of the crowd, that they were able to buy their freedom. By all accounts, they were the pin-up boys of the Roman amphitheatre. Not surprising, looking at those physiques, and they would have been showmen, too. No wonder they used to make the women sit in the upper seats of the amphitheatre!
Apparently, they had a pension scheme (for those who lived long enough), which was extended to wives/partners and any offspring, while their medical care was better than many. Quite a bit of surgical expertise arose from the injuries sustained in battle and the amphitheatre. (Apparently some surgical instruments have not changed all that much in appearance since those times.)
Very hard and brutal times, but interesting. Wouldn't have liked to have lived then, though.