just hope we don't see a "toboggan run" down this steep slope when everyone xfers their BTC to USD in a panic to get ROI back.
Why would anyone want to convert a promising sound currency for an exponentially-printed-to-oblivion/give-inflation-to-bankers-enslave-everyone-else/no-control-over-your-money corrupt currency?
There are people who-need-to-pay-bills-in-USD-and-dont-holding-much-USD-anymore.
I agree, spend USD first, but when you dont have more, you need to use BTC

there are ~3.600BTC a day, imagine the impact each and every miner would really sell all mined coins each day
..exactly, it won't matter at all as it would be 10-15% of coins transfered in 1h, stop hunting ghosts
some data from bitcoinwatch.com
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Total BTC 11,942,925 BTC
Market Cap based on latest prices 2,340,813,300 USD
or 1,849,959,083 EUR
or 7,738,895,971 PLN
or 1,569,491,193 GBP
Transactions last 24h 37,057
Transactions avg. per hour 1544.04
Bitcoins sent last 24h 590,528.10 BTC
Bitcoins sent avg. per hour 24,605.34 BTC