tl;dr -- this game clearly plays out very differently as a noob than a veteran.
That sums the situation quite well. It is very difficult to balance for both extremes and maybe the way forward are multiple modes like the existing iron mode.
An iron mode without Hull Restoration could be a solution to the money overflow. After every fight you need to buy new ships or repair your D-modded ones. Ship repairs would be a constant money sink, even in the late game.
As others have said, it all comes down to experience. I play iron mode, never do dedicated smuggling runs, and never take hull restoration, and I'm still swimming in credits. I don't even particularly
try to make money, but just take the good opportunities that are around me and do missions clustered in the general direction I want to explore. I consider hull restoration to be, for a veteran, the weakest capstone skill (and industry the weakest branch, again for veterans for whom managing logistics and money is easy). For someone who's
not a veteran, the constant upkeep/fuel/officer costs, costs of repairing ships, etc, can be a serious burden that threatens to death spiral the game, so industry is a great skill branch for them.
As an example of an opportunity that might not be obvious: piracy of any convoy that has heavy armaments (and to a lesser extent supplies). If you see one flying, or see one pop up on the intel feed, taking a modest rep hit or a detour, then selling to either a perpetual shortage or possibly the one that was just made, will net between 250k and 750k (and sometimes more) for often a quite easy fight right in the core systems.