With a government shutdown in place and two intransigent political parties staring each other down, the urge to hit the panic button is palpable. When the largest economy in the world is essentially headless, who wouldn’t be tempted to run for the exits and raise a little cash?This primal fear is precisely why market timing remains the perennial, most destructive "Stupid Investment Trick" of all time.The Political Storm vs. The Market TideThe anxiety you feel watching the news is understandable, but history suggests that running for the exits is an objectively bad financial bet.Consider the facts related to government shutdowns and market performance:In the six shutdowns since 1990, the market was up one year later in five of them. In fact, one year after the longest shutdown ever (34 days, starting in December 2018), the market was up by a staggering 33%.That is a devastating loss for anyone who sold based on fear and political noise.The One Mistake You Can’t UndoWhen you sell out of fear, you don’t just lose a week of gains; you surrender your ability to compound wealth for your entire financial future.You must be right twice: You must know when to get out and when to get back in. Getting both calls right is an act of pure financial sorcery.The Compounding Loss is Permanent: Once you lose those market gains, you never get them back. Ever. Sure, your portfolio might increase from your new entry point, but it will always be off of a permanently lower base. That is no way to reach your goal of buying a house, putting a kid through college, or securing your retirement.If you have a financial advisor urging you to time the market, ask yourself: If anyone knew how to consistently time the market, why would they need to sell me on the idea?The World Has Ended 100 TimesYour portfolio has weathered worse storms than this political gridlock.Over the last century, investors who stayed the course endured a world war, the dropping of a nuclear bomb, a Great Depression, a Great Recession, a presidential assassination, and a global pandemic.Through it all, the S&P 500—the proxy for the market at large—has climbed from an index value of about 17 to a current level of almost 6,500. For those who simply stayed in the game and reinvested their dividends, that translates to an annualized total return of a bit over 10%.The Only Question That MattersFinally, remember your diversification is your protection. If you have a properly allocated portfolio, you are not simply holding "the market." You have bonds, cash, foreign stocks, and other assets precisely to protect you against shocks like government shutdowns.In the battle of fear versus compounding, compounding always wins. Stick to your plan, trust your asset allocation, and when the political noise gets loud, remember the question is not "Should I Stay or Should I Go?"For your portfolio, the answer is always stay.