Not everyone was a citizen though, there was a significant underclass who had no shares.
One character was a celebrity in some sort of combat game who was followed by camera drones & used drugs to suppress puberty so he waa an eternal 'child', I have the impression that medical science allowed virtual immortality short of accidents.
One character (may have been the same one) had had a 'previous life' & had committed personality suicide by some form of mind wipe bequeathing his worldly possessions to the new personality that would eventually develop in his old body.
I think the motive for this 'suicide' was essentially boredom, he'd lived a long time.
The mind wipe in question was pretty extensive & all encompassing, he had to be cared for & educated from scratch as if a newborn baby in an adult body, nappies & all (but I'm pretty sure this was purely backstory in the book I read).
He also had miniature nano organisms (or bots?) like miniature worms or millipedes that complimented his immune system & aided healing, they were self replicating, pretty sure they were some sort of bioengineered organism tailored to his DNA rather than bots but not 100% on that.
There was an organism spanning a large area on the planet that absorbed (or consumed) anything that wandered into it but saved the DNA of anything it had previously absorbed & might randomly reproduce any animal plant or individual it had previously absorbed fully formed.
One of the characters fell into this but got pulled out before the full effects took hold, as a result he grew leaves from his head & his immune system was then constantly battling with the 'infection'.
When did I read this? probably some time in the 80's in the UK.
When was it written? I haven't a clue, sorry.
It was a paperback, probably something I had out of a library, because I never get rid of anything I've bought myself so I'd still have it & be able to dig it out if it wasn't a library loan.
I have lots of fragments of world background & 'colour' that seem to have stuck in my mind there, but a complete lack of any story arc to go with them.