Patrick was aware of the risk. He only keeps 10% and many people paid with other payment options. People who kept 100% made a significant loss.
Exactly. Comparing to their total sales, loss on BTC price decline is very insignificant. Their total bitcoin sales in 2014 were only ~$3m, they keep 10% so it's only $300k worth.
Assuming BTC drop from $600 to $240, that's decline of 60%. That's $180k in the worst case scenario, assuming all the sales were made when BTC was at $600, realistically probably less than half of that (so $90k).
Overstock's total revenue for 2014: $1,497m ($1.5 billion), up by 15% on 2013 ($1,304m). Net profit (after tax, salaries and all the expenses) was $8.8m.
So basically we're talking about something between 0.006% - 0.012% (worst case) of revenue. Completely immaterial.