Is the ultimate irony of the posse that they're all way more capable than the underachievers they're portrayed to be?
Through out my childhood, I loved red dwarf and still go back to it as an adult. One thing I realised now as an adult that despite Lister, Rimmer, Cat and Kryten being deemed the bottom of society when humanity still existed, (aside from Cat who was the bottom of his species society) they have all successfully navigated 3 million years into deep space with basically no qualifications. I can't help but think how exceptional these four people are in their own fictional universe.
Through out the show, we constantly see the guys overcome perilous situations some that wiped out entire space crafts (way more advanced than red dwarf) full of officers and scientists way more qualified than themselves. (Think the Psirens, The Despair Squid, The Holovirus, The Epideme Virus, etc)
Ironically Rimmer dreamed of being an officer, but as a hologram his space adventures have been more profound than anything a navigation officer could dream of. He's done a good job of keeping the last human alive sane, no one else could have done it as a hologram. Kochanski would have made Lister depressed, Hollister would have ruled over Lister with an iron fist, and Peterson would likely encourage Lister to drink his sorrows away.
Lister was the ultimate slob pre-stasis, the lowest rank on the ship, only cared about getting drunk with mates and eating curry, but still seen as a bright guy who could amount to so much more if he applied himself. Thanks to Stasis, Lister did reach that potential, being the last human alive made him buckle down out of pure survival. He shows incredible resolve despite the existential dread of his situation and refuses to die when most would just give up. (Think the White Hole, The Justice World, The Inquisitor)
Kryten was always treated like second rate machine who's only purpose was to be a personal butler that did all the dirty work. However through out the show, we come to see he's actually a very sophisticated mechanoid capable of complex thought and introspection that models more advanced than him can't comprehend. (Think Hudzen-10) He's also a walking encyclopedia in a broad range of subjects and frequently makes astute observations that have saved Lister, Rimmer, and Cat countless times. (Think the Psiren disguised as a meteor).
Cat was abandoned by the rest of his species for how stupid and uncool he was. He grew up alone, living a purely hedonistic life, either eating, sleeping, obsessing over outfits and his self image. When the Posse formed, they gave him direction in life and he became a valued asset. Despite his chaotic nature, he's shown to be a competent pilot, possibly the best with a gun out of the whole crew, and his enhanced senses help with tracking and survival.
When you put them altogether they somehow make possibly the most exceptional crew in the history of the Red Dwarf universe, given how they have the most difficult assignment imaginable with no blueprint. Looking at Red Dwarf through this lens, has made me appreciate the show as a touching story about the rejects of society rising up and amounting to something to greater than the labels bestowed upon them.