If someone believes he is happy, he is happy.
If someone believes he is the lucky, he is not necessarily lucky.
Seeing the world rose colored glasses does not make you any luckier, it makes you happier. By only asking for those that self-identified as lucky or unlucky, he has failed to isolate the variable of happiness.
Here is an excerpt from the book which points out the author's faulty reasoning.
"On average both `lucky' and `unlucky' participants lost about £2.50. Wiseman's conclusion: `The results indicated that luck wasn't due to psychic ability'."
In this quote it is revealed that the people who "felt" lucky really weren't lucky. In fact, they were about as lucky as the people who felt unlucky. The people who were "lucky" also expected to win twice as much as people who felt "unlucky". So his whole experiment is flawed.
This is the type of optimism hawked by many self-help gurus. But then again, it doesn't really matter if your situation really has improved with these "tips" as the Romans found out with church and bread and circuses. Keep the plebs amused and fearful and they will willfully ignore everything else.