Personally, I am bewildered more than angry about paranormal claims, but you're damn right I'm angry about some of the implications of these claims.
- When someone claims they can cure some ailment based on zero evidence, people suffer. Usually, these are vulnerable people, clinging to false hope. It is entirely despicable to offer them that hope when it doesn't exist.
- When the Catholic church spreads lies in 3rd world countries about the effectiveness of condoms, solely to pursue their cockamamie and anti-human prohibition against contraception, people suffer in the millions.
- When people condemn others for aborting babies (or for that matter, murder in the name of Christianity doctors who have carried out abortions) babies and parents (and the occasional doctor) both suffer.
- When someone is convinced to make important decisions based on superstitions like astrology, tarot or any other kind of vapid bullshit, they can only coincidentally make the right one. Which leads to suffering.
- When 'psychics' lead on the vulnerable, whether it be via supposed messages from lost loved ones; wasting police time and screwing with people's emotions with their disgraceful and inevitable clamoring for attention whenever anyone goes publicly missing; actively and deliberately conning them out of money; or conspiring to keep them deluded, it certainly isn't the 'psychics' who suffer. But the suckers inevitably do.
- When a Christian lobby argues that children should be taught that the world is 6000 years old and that evolution is false, those children suffer because they are being taught lies. This does not equip them to live well in this world, because it puts pure bullshit at the core of their ideology and teaches them to ignore evidence if it contradicts what they are told by their parents, their church or - sickeningly - their teacher. It can also blind children to a lot of the beauty in the world about them. I find it difficult to understand why anyone would rate obedience to some god as more beautiful and worthwhile than understanding how the world really and demonstrably works.
- When the religious in general perpetuate their ideologies to children, they are restricting the choices those children can make or are at least making it more difficult for the children to make different choices. This is a form of suffering because it may easily prevent a child from living up to its full potential. It also constitutes indoctrination, which virtually every ideology tends to classify as wrong. Proponents of non-ideologies such as atheism certainly tend to think of indoctrination of any kind to be wrong. We prefer to teach critical thinking so that children are properly - formidably - equipped to decide.
- More importantly, those parents are retarding their children's' abilities to think critically and are indoctrinating them with dogmatic assertions without evidence that these assertions are correct. This can cripple children mentally and emotionally. How are they to tell what is true from false if they are taught to believe without question what their parents (priests, imams, whatever) tell them? Suffering can't be far behind.
- When people con gullible but otherwise intelligent and competent people and businesses with pseudo scientific promises such as perpetual motion and free energy, they are absorbing money that could be used for the genuine betterment of the world. Investors in this kind of thing tend to want to help people as well as make money. They would be better off (on both counts) investing in genuine research programmes. People suffer while all this chicanery is going on.
- When parents tell their children about hellfire, it is a disgusting form of attempted control, almost guaranteed to spread the myth to the subsequent generation. But it constitutes child abuse. Frightening children to be good is deplorable in itself as there are plenty of other, less brutal methods. But frightening children with hellfire in eternity is nothing short of evil. Who suffers? Everyone who is brought up in such a tradition and doesn't have the luck to realise it is dubious.
- When people fly planes into buildings, it is fairly obvious who suffers. The immediate victims were just the tip of the iceberg: the act triggered a poorly-justified and incoherent war. Who really ends up suffering in the end? Well, troops and their families, of course, but also people who are having their country ripped apart because sabre-rattling got way out of hand.
I wonder if I'm committing a 'don't hate the sinner, hate the sin' fallacy here. Perhaps. I'm angry that society seems determined to perpetuate idiotic notions, often for ignoble reasons. I'm angry at some of the bullshitters as well, although some of them are more deserving of sympathy and many of them - I'm almost certain - are entirely sincere in their beliefs. Most of all, I'm angry that suffering can be caused by deliberate ignorance, in this day and age. The moment you accept something without evidence or without a method to revise that thing as evidence changes, somebody starts to suffer.
People have suffered because of rationality and because of science too, of course. This is regrettable. But the saving grace is that the rationalists and scientists realised they were mistakes and tried to correct them, rather than trying to justify the carnage. These incidents have taught scientists - and society - to be more careful. Sadly, this doesn't happen where faith is involved.
I can't speak for other skeptics, but I would guess that a lot of us are angry at the consequences in the way I've described. We don't really tend to want to wipe out supernatural thinking and we tend to believe in the right of people to believe bullshit if they want. However, we do object to people suffering because of belief in bullshit and we do object to bullshit being perpetuated to future generations - aided and abetted by society - as though it doesn't have to live up to the same standards of evidence as anything else.
Now I'm really interested to find out why so many religious people get so angry at atheists.