maybe this will help: you see a man rushing along and he notices a twenty dollar bill. He starts moving toward it but looks at his watch and rushes off.
You pick the bill up, and it is indeed $20.
Why didn't the man pick it up? It's free money.
It's true that it's free money. However, the man might have something that he's rushing to that in that instance, he's decided is worth more than $20. Perhaps it's a very important job interview, for example.
So while it is a free $20, it also costs him a job. that's why he can't afford to pick it up.
You don't have the same opportunity cost. For you the $20 didn't potentially cost a job. So you pick it up.
Developers are perhaps in a similar situation.
Let's say there is a bug that is so horrendous, every month 5% of your userbase leaves saying "We are leaving because you don't do x." Another 5% of your userbase is on forums desperately asking for x, saying they will start paying you the moment you do it.
Why don't you pick up all these customers? All you have to do is x!
Perhaps the reason you're not picking up these customers is because you have another feature that increases your reach by a factor of 5. So, although you could retain 5% of your users who are leaving, and pick up 5% of users who would join, you have another 500% of your users who you are buying by investing your time in doing y instead of x.
You can't "afford" to do x, because then you wouldn't be doing y.
In essence, you are rushing to an interview instead of picking up the bills your customers and potential customers are waving in front of you hoping you'll take it.
Is your analysis of the opportunity cost rational and correct? Maybe not.
But this mentality does explain why a whole lot of software is extremely buggy and has forums full of people asking for simple bug fixes and features, all of which are ignored while the company pursues new customers. The company feels they "can't afford" to incur the opportunity cost of fixing their bugs, because they'd be losing out on the new customers they could be getting by focusing on new features instead.
This is also why making a big scene in the news gets a bug fixed very fast. Now you're not just "paying" with your dollars, which the company would ordinarily snub. you're paying with the dollars of all the new customers who are reading about their response in the press; and the company cares a lot more about those new customers than it does about you. so it fixes your bug, because now it can't afford not to.