No, it is the dev's fault because they allowed such disparity in rewards in the first place. Humans will just go for the path of least resistance.
It is also the devs fault because they didn't include any compelling reasons to do anything in this game other than credits. The only exception would be missions to unlock the engineers, but there are no missions that offer anything unique, or an activity that is actually fun and engaging.
My recommendation, stop blaming youself, and wait for the devs to complete the game. Play something fun in the meantime.
If it is truly all the fault of the devs, (though I don't for a moment think they do not share the blame) then how come the real role players amongst us still manage to resist the temptation and still play within the character we create?
I don't smuggle, I don't pirate, I don't deal in *slaves nor narcotics nor illicit weapons.
I don't deal with black markets nor terrorists.
Because of this, I can't unlock most of the engineers. It puts me at a disadvantage without a self nerf.
I don't employ exploits.
I don't pledge to a PP power just to get their special weapon, and then betray them for the next.
Because of this I have no special weapons and without a self nerf have more challenge.
I don't rush to get King/Admiral in a week to fly a cutter or a corvette.
I made money instead in exploration and trade, and so fly an Anaconda, a Python etc with a few rebuys.
I have role played this game for years, and have almost a billion. If I'd used exploits, I'd have multiple billions.
The game is not at fault here.
It is possible yes to complete every challenge and get every ship, every weapon in a few weeks and engineer them all to a PvP meta.
But those who play that game are not playing elite: dangerous.
They are in the game, but they are not playing.
They just skirt the limits of what's allowed
Exploiting the fact that FDev didn't foresee this kind of play because as a games company they lack experience.
They rush to get what they consider "end game ships" in the shortest time, and to those who play the game as designed, they say "git gud".
It is no wonder they claim there is nothing to do.
They aren't playing elite, they are playing Dark Souls in spaceships and most of them would have better spent their money in Eve.
But there is hope. More if FDev reset the galaxy after balancing.
The game was meant to be a 10 year climb to be elite, the best.
What use is spending on any game if you always take the shortest, easiest path to the end?