Making a mistake is not in-it-of-itself a problem. Mistakes are inevitable, if nothing else because people cannot be oracles. If you bet into the river because you have a flush draw, you'll lose around 75% of the time - but that doesn't mean it was a mistake in those 3/4s of a time.

If as a board you unduly punish executives when bets they make don't pan out, you risk causing a culture of fear that prevents innovation and big bets.

Obviously there's a limit, and the reasoning is important behind the bets.

That being said it's not like all of the tech ceos were perfectly competent - that's not what I'm saying. But the knee-jerk "well, fire them too" reaction from the internet is mostly an emotional response.