The concept of 'gambling' in chess must seem like anaethma to chess purists who view the game as the ultimate test of skill rather than luck. But the idea is that instead of intensive calculation over the board, one rather relies on positional intuition when considering a material sacrifice. In blitz chess where time is critical, this is definitely a skill worth developing.
The theory is that over the course of hundreds - if not thousands - of blitz games, one's sense of when to 'gamble' and when not should gradually improve. So in blitz I gamble all the time - thus far it's 'break even' since I lose as many gambles as I win and rating remains constant at about 1300. But in every game expect sparks to fly - here is an example involving the interesting Diemer Duhm gambit in the French Defense. The 'gamble' in this game is the bishop sac 12. Bxh6 and had white effected his captures on f6 the right way round with 16. Rxf6! insteand of 16. Nxf6 ??, there would have been no defence (at least not that I can see!) against the threatened mate on h7.