The younger you are when you commit the mistake, generally the more fearful you are of the result of that mistake. That same mistake might get a "well that sucks" from someone who's been around the block.
Tech for 12 years and I've never made a mistake disastrous enough to be fearful for my job. The worst costing ~$20k in hardware (couple server CPUs). Told my manager right after without hesitation (this was also at a startup).
I would not stress that much anyway now if it were to occur. Having been through mass layoffs from startups twice before, you change and become hardier. I will be careful but will never be fearful of employment. Short of doing a Desk Pop[0], I'm falling asleep every night with both eyes closed. Life is too short as is. Let me go and I will spend my next morning on a nearby beach with a good book.
Just curious, how did you destroy the CPUs? Was it physical maintenance or did you set the wrong voltage/etc (usually this happens during overclocking in consumer-grade machines which is why I’m curious how this happens on server machines).
I've made mistakes, and even big ones, but I've never worked for an (technical) employee abusive enough that I thought they were going to fire me for a single mistake.
It's not that they don't fire for mistakes, it's that they work with you to correct your behavior first and they give plenty of warning to someone who is in danger of that.
And I've never been given that warning.
edit: Added the word "technical". I've worked for companies that would fire at the drop of a hat, but they were all retail minimum-wage jobs.
Hmm. I'm not sure I've ever had a screw up I thought would get me fired and I've been in tech for 13 years. I've definitely had some pretty big screw ups (turned the lights off for over 200 people, see my reply to parent). I guess I've always had managers who had my back.
I've made mistakes, though thankfully no huge outage-causing ones. The only "I'm going to get fired" mistake was a political one, where I accidentally emailed a report to someone, and was informed after the fact that it was a very bad thing.
It's also a fallacy to believe that making mistakes in the past and learning from them precludes making many novel mistakes in the future. Kind of like the disclaimer that's always given about investing. Both the individual and the organization must simply bake in as many failsafes in their processes as possible. And even then, sometimes Murphy's Law manages to slip through all the holes at once.
Tell me about a time you made a mistake that you thought was going to get you fired.
1. Everyone has one. If you don't, you haven't been doing this long enough and I want you to make a couple of those mistakes elsewhere first.
2. If you didn't learn anything from it, you're going to make that and bigger mistakes in your hubris. I'd rather you do that elsewhere.