this might be a really stupid tadc theory but i saw people theorizing that the cast are actually dying in real life and abstraction is their death and wanted to expand on that by throwing in that kinger made the circus for his dying wife so they could spend the rest of her life together happy and without pain and going on fun adventures. he also didnt make an exit because he fully intended on dying there with her. as for the rest of the cast, i dont necessarily think that they were all dying before they put the headset on, but maybe the pod thing is real and the cause of death is just the battery running out or the pod failing or something that causes their life support to stop working and their bodies gradually die. since jax is the most recent example of almost abstraction, i think instead of his pod failing its more like his severe anxiety is causing him to experience abstraction like symptoms. as someone who used to have severe anxiety myself and also refused to get help for a while due to fear and pride, i kinda relate in that sense. to explain it a bit more, anxiety convinces your brain that your life is in danger even if its not, so since jax likely hasnt had therapy ever in his life he doesnt know what it is or how to deal with it. in those moments hes probably convinced hes dying, so his body responds according and starts to "abstract"
to expand more on the idea of abstraction being their final death: when you die your brain tries its hardest to find any way to stay alive, so basically since their consciousness is in the circus they start acting more and more frantic over time trying to find the exit because as far as their brain knows, the circus is causing their death
as for caine, kinger could've made him with the intentions of making sure he didnt know the story of the adventures so he could experience everything with queenie together. bubble was made to be comedic relief, probably. but as more people joined the circus and probably ended up desperate to leave, caine took it that they didn't like his adventures (the one thing he was made for) and tried to do something with their brains to see if A) he could find out what they liked to make better adventures or B) he could alter their preferences so they liked his adventures and wanted to stay. this likely backfired after he experimented with scratch too much and caused their brains to likely have a stroke and die (or something along the lines of brain failure)
anyways its 2:30am so im likely out of my mind if you have any questions i would be happy to answer u can leave them in my inbox or just comment or whatever i also accept insults if you think this is dumb as fuck thank you and goodnight