Some chess questions about improvement

Why do so many chess players only draw winning positions, or lose drawing ones? Why do many continually slip into time trouble, despite vowing after every game to move more quickly? How can a player perform like a grandmaster on one day and a complete novice the next? What's the best way to beat a lower rated player and what gives you the best chance against a higher rated one? Maybe they need more training and great amount of knowledge about the three important phases : opening, middlegame and endgame!