Is there a point in NATO anymore?

In NATO, isn't America getting screwed? We pay more than any other nation and we put more burden on ourselves than these European nations. In February NATO Secretary General Anders Fogh Rasmussen said that over the past two years, "defense spending by NATO's European member nations has shrunk by some 45 billion dollars" - the equivalent of Germany's entire annual defense budget. Aren't we getting screwed? The Libya mission, shows the European nations weakness, they can't keep up a mission for a couple months, try 10 years! Even though some Europeans nations have sacrificed lives in Iraq and Afghanistan, for the most part we have been in the front lines, and most of them are humanitarian support etc. Is it time for US to go at it alone, aren't we already? Should we drop out, bring our money back to America help people, and invest in our defense? Thanks.