The dynamics of urban decay isn't a matter of leftists only. Often, but not solely, it's kick-started by rightists. It includes bias against hiring specific members of the social strata, investing money outside the local community, including tax dollars, thus not funding existing or new infrastructure, the usual bigotry to keep targeted social and ethnical populations down. Whether it's in minority heavy inner cities, or white heavy rural hill people. But you know humans, they insist on pointing at the other side and claiming everything is someone else's fault, while denying their own contributions to blithe.
It's done to nations too, where namely profit hungry rightists come in, rape the country of resources, and leave ruin behind, then talk about how disgusting the nation is, and/or make them dependent on the rapists. Whose sole purpose is to further exploit them, squeezing every last drop of profit possible. Rightists aren't remotely as holy as they try to make themselves seem. Not that leftists are any better, hypocrisy favors no single political faction.