For individuals, what are the actual security risks of not installing security updates

To be clear, I'm not looking for advice here, but explanations to help me understand computer security better. My web searches don't seem to produce anything usable, mostly just cybersecurity companies saying super vague things that are often apparently aimed at companies rather than individual users.

What can actually happen if you're using an outdated browser, for example? Or even your entire OS is outdated, say EOL?

One thing I understand is that internet traffic could be snooped and so …

advice clear companies computer computer security cybersecurity cybersecurity companies don risks searches security security risks security updates super things understand updates web