I buy them when I have some extra USD so mostly at the start of the month, I also buy as much as I can when I see big dips with nothing supporting the downward spiral of the currency, I exchange some for alt-coins as well when a good coin is getting more popular etc...
you are typical fast trader, i like it, im trader too, sometimes i buying bitcoin for buying altcoin, then get the profit from altcoinn.
now im buying bitcoin just for buying ethereum classic, hope next month will rise to 0.006 again
