The simple answer to OP's question is that carriers don't "justify" anything. Carriers set price based on demand. If the price is too high, aircraft will go out empty and carriers will do some combination of cut fares, cut frequencies & routes, and go bankrupt.
Contrary to OP's assertion which is not based on any reasonable analysis, fares are lower today than in 1985, when adjusted for the cost of living.
OP's fundamental problem is that it is my guess that someone is paying that "insane" price and whether that person is "insane" is irrelevant unless dangerous, in which case he should not be traveling.
As an alternative, if price rather than destination is your sole determinant, why not fly to EDI rather than SFO?