...to have won nothing.
Well there are a lot of unfortunate underachievers. For me the top 5 have to be:
1.) Hungary Team of 1954 WC Final (lost to West Germany). Puskas and his men were the favourites; since then Hungarian football has never risen to the same height.
2.) Indian Cricket Team in 1996 Cricket WC Semi-Final. I was there actually; the pitch started cracking up, and the Indian Team really fell apart to some unplayable deliveries. The Eden Gardens, Kolkata Crowd really lost it (worst display of crowd behaviour I've seen,) and the match umpire awarded the game to the Srils. Tendulkar in his prime, and an Indian squad brimming with talent (Srinath, Azhar in his non-cheating prime, and Kambli at the crease!)
3.) 1974 Dutch WC Team. Cruijff and total football fail against Germany. I hate it when beautiful football fails.
4.) US National Basketball Team at the Summer Olympics. Squad of stars falls apart. Iverson....need I say more?
5.) England Euro 2004. Rooney in his 'supposed unlosable' prime, and what some said was one of the best and most 'gelled' English teams with one of the world's best midfields at that time.