Yeah, but this is the point. It really depends on the context.
Trying to fix every bug in the pure informational website but missing your product launch?
Not worth it, just fix it later. (or not at all, have you surfed the web with the console open? It is flooded with warnings and errors)
But miss the critical bug in the webshop, that cause customers to legally buy for free? That is expensive.
As a software engineer who has been mostly focused on testing over the last few years and leading a team focused on this, it's clear to me now that balancing what's worth testing and what's not is a delicate art and very difficult to always get right.
I do believe that a common failure is not investing in adequate regression focused tests. I've been on projects were these were not in place and an update lost a company millions of dollars very quickly prior to being noticed in production, I've been on projects were delaying any further to release would have lost critical learning data during a period of time that could not be guaranteed to come again quickly (for example market volatility or turmoil).
The best engineers in my opinion love testing as much as building new features because they understand that production fire fighting is the least fun activity of all.
Quick plug, I believe solid test reporting makes the ROI on test development clearer. I'm founder at Tesults - a test results reporting app (https://www.tesults.com) and I'd love your feedback on it, send me an email if you have a moment.
Trying to fix every bug in the pure informational website but missing your product launch? Not worth it, just fix it later. (or not at all, have you surfed the web with the console open? It is flooded with warnings and errors)
But miss the critical bug in the webshop, that cause customers to legally buy for free? That is expensive.