This is where a many traders have lost money and don't understand why. When I was trading AAPL as a MM, a customer bought 100 OTM calls just before earnings, where earnings were thursday night before expiration. After earning, there was one trading left. The stock went up around 10%, yet the calls were down a 1/8 (Yes, long time ago). The customer sent his broker into the crowd to complain that he was right, AAPL went up, but he lost money. He was long deltas, but also long a lot of vega with a lot of theta decay. The stock did not move enough to for the current options prices and he ignored the risk of the other greeks.
Bob
Yes, one has to be in one of these positions at some time to truly appreciate how much of an impact IV has on an options position...Realistically, one can get direction completely wrong, but if they buy low IV they could still come out a winner (I'm sure it happens a bit more in individual equities), but I saw it firsthand last 8/24 and once against post-Brexit...