It's a direct result of their shortsighted, nationalistic decision. The article says it's motivated by a hope of remaining a global economic power, after...breaking existing ties with a global economic power.
You say short sighted. Brexiteers say it is long sighted, so long sighted in fact that Remainers struggle to see any sense in it. Which is where all the "populist" "nationalistic" "racist" "they didn't understand what they were voting for" labels came from.