Its hard to say where to argue that cryonics is garbage to people who kindof believe in it. Every argument in its favor argues from the standpoint that virtaully anything will be possible with future nanobots to the point where it looks like magic in todays world. So why not go from there, since no one is arguing that its possible with anything approaching todays tech.
1. Most cryonists expect to die of what is considered to be nearly old age. Some brain abilities peak at say, 5-8 years old(subconscious language and culture acquisition) . Some at 14(simple reaction time) . Others in the mid-late 20's(some measures of working memory). However, its basically known that say, starting at about 33 years old, *everything* starts going downhill besides some measures of long term memory. So, people expect cryonics to not only bring them back from the dead, and all the magic that entails, but have that technology make what may be a 90 year old brain that perhaps has alzhemirs and dementia young again(In order to live a proper life).
So, more or less a total reverse engineering of the brain.
2. Immortality. So, say you die of cancer at the age of 70 with heart problems. So, after reviving your brain, for you to go back to normal, we must have cured everythign else that ails you.Why? Are we just going to revive you for you to die again in 15 years?
3. Total DNA knowledge. Degenerative disease, the telomere replication problem, and all that. To get something like *you*, we gotta reverse engineer and fix your dying dna that as it gets older keeps having more and more replication problems.
So there is also more or less a near total knowledge of DNA and its information.
4. What else could you be made from or revived from at that level?
At *that* level of tech, you might as well be a giant blob of 600 lbs of blended variety of farmers market food and animal meats and fats to ensure all of that chemicals that makes a human nanotech could work with, have some of your DNA saved(assuming no horrific life experiences and middle class+ upbringing, supposedly DNA determines 80% of who you are, and around 50% even under poverty and a poor upbringing), and just a very honest autobiography and record of yourself(giving most of the rest of you), and something about 95%+ similar to who you were could be created. Would you be made from that?
5. What does an effectively all-knowing brain do?
And with that level of tech, with a total reverse engineering of the brain and DNA, making some 500 IQ brain blob probably isn't much larger of a challenge. We already reverse engineered intelligence with nanobots, remember? With something like that making decisions, its basically unpredictable as to what society would like like.
7. Clear strong potential of abuse. We may not even want it to take off, based on natural human corruption. The alcor guys recommend that even in a case where one suspects foul play, one does not get their body dissected so their brain has a chance of living forevor. That's a kind of belief that one writes in dystopias of companies blending with psuedo religions like scientology to take advantage of.
On that topic, for those only freezing their brains, where does the rest of the body come from? Does it come from your DNA? Are there accelerated growth bodies made? Is it all magical nanotech? You can't just replace your various hormonal glands with someone elses and be the "same" person, since that's a huge part of your emotional life. Is that body grown out of a giant meat vat?
So, what type of fraud do I believe it is? I don't think its necessirally the type of fraud the homeopathy guys do. This is the type that I believe would arise naturally out of hope, with a good amount of those running the facility believe in to. So its a scam, but I don't think its like the occasional MBA's from top schools who decide to run a homeopathy business.