Isolationism leads to wars, refer back to WW2...Also if anything a more stable and productive world economy would increase our standard of living. As of now our domestic products suck, we pretty much depend on foreign markets. Isolationism would destroy our country.
People think that we don't have jobs now, wait until they had to buy stuff made at American union wages. All those parts and labor we are used to getting so cheaply who go up exponentially in price, and induce hyperinflation to our economy. Not to mention it would dry up our sources of some of our best intelectuals that are now becoming our doctors and scientists, because of how far behind the American education system has fallen behind the industrialized world, because it relies on making sure as many people as possible graduate, instead of preparing them for higher education and the work force.
And I could go on and on with this but I won't bore people anymore.
But don't let reality get in the way of a comedy routine...