Velocity is relevant when the trades are in exchange for goods and services, which applies to everything I wrote in the posts upthread.
A bitcoin is a goody. If you sell a bitcoin to me and buy it back tomorrow, we won't have additional GDP. Additional credit (debt) leads to additional GDP.
It depends on how you compute the GDP. As far as I know, currency exchanges are not counted as goods and services in the computation of GDP. However, purchases and sales of assets I believe are counted. When you buy and sell a house, this indeed does cause people in the economy to earn salaries and commissions, and thus does increase the GDP. Buy and selling BTC does also to some extent.
Sorry if you are arguing that velocity of money has no relationship to GDP, then I should just ignore you as being retarded. It is quite obvious that the rate at which money changes hands in the economy, effects the amount of salaries and commissions earned by humans and thus the level of the economic activity.