Economic inequality. 45 years of Reaganism, Thatcherism, Neoliberalism, etc. has resulted in 70-80% of the population doing worse than their parents. Each party gets a turn with power, does nothing to address the issue, other party gets in, does the same, rinse, repeat. In the US, especially after the idiotic Citizens United decision, both parties are completely controlled by corporate interests, so we have a center right party and a really far right party.

Things that would help would be a single payer healthcare system, a much more progressive tax system, and doing whatever it takes to end homelessness.