Countries frequently try to weaken their currencies in an effort to boost exports and ultimately the economy. However, once one country does it, others want to follow it, and currency wars can result. However, once currency depreciation no longer works and the economy keeps under performing, politicians want to find someone to blame and usually end up blaming other countries. As such, government start adopting isolationist policies which limits trade. Their way of thinking revolves around the idea that by limiting international trade they keep jobs at home and thereby help their country. However, international trade is often a great solution for overcoming and efficiencies. For example, it should be obvious why Switzerland is better off importing oranges from Greece rather than growing them itself due to the climate issues or how rich countries stop importing easy to manufacture goods from countries with cheaper labor costs and instead produce those goods themselves.
Those products might end up being ridiculously expensive. It is kind of like paying a rocket scientist who charges $300 per hour to clean your house. You can do it, but it is a waste of money. Also, it is usually only a matter of time until things degenerate politically. It is easy to think that countries can simply limit certain imports and everything else will be fine. But once country A implements an isolationist policy against country B, country B will retaliate and so on. Therefore, in the real world, isolationist policies tend to be taken too far for the political reasons. The main risk should come as no surprise. Trade wars can end up gradually increasing tensions among countries and as such real wars can follow.