It would be interesting to enumerate Hitler's successes as a gambler
1) Reintroduction of conscription: success
2) Revoking the treaty of Versailles: success
3) Rearmament, including weapons prohibited in the Versailles treaty: success
4) Reoccupation of the Rhineland: success
5) Anschluss: success
6) Sudetenland: success
7) Occupation of Bohemia and Moravia: success
8) Norway: success
9) France: success
10) Crete: success
Norway and Crete were admittedly costly successes.
Up to this point, he had displayed all the attributes of a gambler to an exceptional degree, i.e the ability to bluff and deceive his opponents, gauging the weakness of his enemies, nerves of steel, and recognising the probable strength of the hand he was playing. As far as France is concerned, it was not a "bad gamble", since Hitler was very well aware of the fact that the French were demoralised by years of factional politics. Manstein's plan, which Hitler endorsed, did carry the risk of exposing a deeply penetrating spearhead to encirclement, but it utilised the assets the Germans had, i.e a superior air-force, and a large, highly-trained and battle tested armoured force. The choice was between a risky operational plan and economic strangulation. Circumstances justified his decision, as did the result.
Hitler failed because his gambler's instincts failed when judging the resolve of the British under Churchill. Also, his calculations were poisoned by his racial view of history, which led him to believe that Russia was some sort of Slavic monkey house, a pejorative term which he actually used about them. This was obviously absurd, and from this point on, his actions became increasingly irrational.