When there is a delta (as there is right now) between price of BTC and cost to produce BTC then every new BTC created is effectively being purchased for less than market value, and as of right now for a fraction of market value. So it would stand to reason that the vast majority will be converted to $$ or other currency immediately upon creation.
I'ld previously made the opposite argument. Back when GPU profitability was low, those miners couldn't save their coins because they were needed to pay the electric bills. When profitability skyrocketed, fewer coins were needed for the electric bill and thus more coins were saved.
There is one part to your argument that I'ld agree with though. There were some people who mined rather than buy specifically so that there was no need to use an exchange to acquire coins used to make purchases. So those people were probably first in line for ASICs and today are getting many more coins than their level of purchases require, thus they can then spend / trade their excess coins as they essentially are considered to have no cost. I don't know how much of the mining capacity might fall in that category but it could have an impact, surely.