What are the costs of cryptocurrency fraud? I have heard many claims that transaction volumes can be "faked" for cryptocurrencies, but I am skeptical about how this is possible. I want someone to walk me through the math describing what you need to believe in order to make money by boosting transaction volumes. 

1) First, assume a constant velocity of money but a positive transaction cost t. Suppose t is relatively high. Is it possible to make money as a market manipulator? What would these profits be? Is there a point where t prevents you from making money as a manipulator? 

2) Second, assume it is possible that coin velocity declines because momentum-driven speculators enter on news that prices rose due to "fake" transaction volumes from the market manipulator. What is the required velocity change as a function of the transaction cost t? 

I am not sure whether I understand the math here, but I suspect that coin manipulation is possible. However, there is a point where t exceeds the possible change in coin velocity, which creates a limit to market manipulation.
For exchanges with no fees, users colluding can sell each other coin backwards and forwards all day to manipulate prices at no cost to themselves. Or you could do it with one user but two accounts. If you are buying and selling at the same time, at the same price, the price doesn't matter.