Except if the original idea of the location of hell ( the demons home) applies. In which case OP better get off world quickly or else he's trapped with a demon
And the gold market collapsing making the bars worthless. Or if that got figured out, the life cycle of the oceans collapsing killing most life on earth.
Get the gold, use a few flakes from one of the gold bars to fill a hula hoop with salt, spend the other trillions of dollars on normal rich villain shit.
This reminds me of that scene in one of the Pirates of the Carribbean movies where Davey Jones has to stand in a bucket of water to go on land for a meeting.
Plot twist, you have to keep the hula hoop up or the demon can get you, because dropping the hoop would inevitably create a break in the salt somewhere.
What if you're dealing with a demon who isn't weak to salt? What if the rules on salt circles require the salt to be on the ground, so a salt ring in orbit does nothing? What if the salt ring doesn't meet the salt density requirement to ward off demons? What if the demon never leaves earth, instead hanging out at a coffee shop, and thus the demon doesn't have to cross the salt circle to get to you? What if the demon simply grabs your soul after you die?
That ring is orientated incorrectly. Other than that there is absolutely nothing wrong with this idea. I'm sure all the sea life can survive having the salt removed from its environment I'm sure it's not necessary to its survival.
The only "demons" salt repels are the bacteria and fungi that want to eat your food and make it rot because our ancestors didn't know what was going on to make food rot and assumed evil spirits. Salt preserves food, thus must be magic. And then the "confirmation" came because anyone who used a salt ring wasn't attacked by evil spirits, so it must really work!