You have your cause and effect backwards. People assume that "the other guy" is constantly doing all the bad stuff in the world and that "their guy" does all the good stuff. They're not hoping the economy tanks to win an election, they're hoping the electorate realizes "the other guy" tanked the economy and now their base will be energized/swing voters will move to their column.

Also, if you don't believe anyone in Europe is rooting for collapses you seem to be ignoring Short positions or how capitalism works. Everywhere in the world, someone benefits from the people in power failing/bad things happening. This isn't an exceptionally American trait.