Unfortunately there are thousands of people that do not believe the Mccann's story. People intelligent enough to see that there is very little evidence to support the abduction claim. Its not that these people wish for Madeleine not to be found,its that they wish for whoever is responsible for her disappearance to be brought to justice.
You are correct Amanda, in that many people do not believe the McCanns, but as to intelligence, how can they openly accuse and threaten people, when there is absolutely no reliable evidence, to back it up, at the risk of being arrested?
I also find it difficult to believe, that anyone would not want the child found and the culprit/s responsible for her disappearance punished.
None of us can say, that we know by whom or in which manner the child disappeared, so wild accusations are just plain silly and irresponsible.
We can all speculate and nothing more, while we await the results of the present investigation.