When the virus can exist, the immune system is not healthy.
Your immune system could be healthy but the Hep B virus is a evolution machine. It is in a constant state of trying to evolve / mutate away from any type of control, be it your immune system or treatment drugs. So any successful mutation by the virus is not a good thing.
Yes, it's a very bad thing. So assuming someone were able to raise their immune defenses significantly through a change of lifestyle, would their immune system be able to combat HBV's different mutated forms by itself, or no?
Probably not because you can't really "raise" your immune system. It is what it is. Once the virus overcome your immune system's bag of tricks, that's it...virus stays.
Hmm... I hear the phrase "weakened immune system" a lot, and it seems some people can fight/effectively prevent diseases without any meds while others need it. I think that's indication that many people do not have a optimally functioning immune system. Even among HepB carriers who were infected since they were very young, not everybody's viral loads get ridiculously high.