Like any good sect, that adopts the best bits from traditional religion but leaves out the inconvenient bits, the secret does the same with reality.
It is true that we are simply manifestations of energy. But the truth is also that opposites attract (in the real world of positive and negative poles of magnets). By spinning ourselves into a ‘positive’ state of expectation, we will sure attract the opposite if science is anything to go by?
It is true that people are by and large responsible for their own miserably lives, but the truth is also that control of our own lives only apply (to the extent required by the secret at least) in very affluent societies where there are limitless opportunities. What holds good in the US of A does not necessarily hold for Rwanda or Iraq.
It is true that we are all ONE in the universe, but every system is in a balanced state that requires equal amounts of positive and negative energy to remain stable. There is good and evil and there will always be. The only state in which pure good may exists is possibly heaven, but here in the world we live protons and electrons. Good can only be recognised because of the contrast of the concept of evil. Happiness is only happiness by contrast to the state of sadness.
The message if the secret (note the lack of capitals) is positive and can, on the face of it, do no harm and is so successful because the time is right. But, trust me World; those teachers are charlatans selling snake oil to the vulnerable.