Bugs cost sales
Bugs will cost you sales.
Last year I was trying to buy a gift from the web store of the oldest corporation in Canada. I added the item to my cart. I entered all my payment (credit card) information in correctly.
I pressed purchase - and nothing happened.
Knowing that sometimes there is a delay and some implementations can do bad things if you spam buttons, I waited. But still, nothing happened, and no errors appeared. I tried again. Same issue.
I opened up Chrome DevTools and tried once more. I saw a request from their backend services that returned an error: “Bad cvv”. I triple-checked my credit card CVV entered, and it was correct. So at least I know it was an issue with that and not my address or the item being out of stock or something. I chose a different payment method, and that worked.
If I hadn’t been a developer, I would have given up, and they would have lost a sale. You can extrapolate based on average sales and average usage of credit cards for payment to estimate the losses for a bug like this.
When deciding on priority or making a case to fix a bug, you can estimate how much it will cost. This will be very compelling for everyone involved. Even better, do this to incentivize test coverage for the potential of such bugs.