What is a well known 'public secret' in the industry you work in that the majority of outsiders are unaware of?

many software developers

Most individuals care about security, but most companies’ reward structure does not reward proactive security measures. Alice will get a much bigger bonus if she spends 20 hours straight fixing a zero-day exploit in the wild than if she had spent a week implementing proper safeguards in the first place.

That's not fair. I care about security a lot. But implementing security takes time, and hiring me for more hours costs more money. So most entities that need software developed want the solution that costs less and is faster to develop, they don't really understand what "security" even means. And the reality is, if you really want security in your software, you're not hiring a dev to make a piece of software, it is a continuous expense to keep the software patched and secured, which is not what most companies want. I'm billing for the hours either way. You just need to point me to the guy who's willing to pay.

And I also don't know anyone who feels incentivized to fix security holes. It's the software equivalent of having to fix the leaky mystery toilet in a dive bar. Yes, the pay might be high, but it's also extremely stressful and you're taking on a lot more responsibility - because it's already too late. Plus it puts a strain on the relationship with the customer who paid you to develop the software, even though we both know they were the ones who didn't want to pay to prevent this in the first place. If you think I'd rather stay on high alert 24 hrs a day thursday-monday to fix some preventable shit, than be at home with my family on the weekend, you're insane. The bonus might make it tolerable. I'd still rather not.

Worth pointing out this isn't usually down to developers choosing not to do it. But management either via direct decision making or deadlines.

It's not that they don't care, not at all. But when you have a road map and hard deadlines you don't have the option. And it's hard to sell security as a priority to leadership when the other option is features that can increase revenue.

It’s only after a major security breach that they fix their security holes.

I had a feeling based on constant news of data breaches.