Sure, nothing comes for free. But new vulnerabilities will be patched, generally quickly, whereas obsolete operating systems will remain vulnerable forever to exploits that are well-known and probably weaponized for script kiddies.
And while change is hard for many people, there aren’t many “essential features” that actually disappear. A particular way of accomplishing a task may no longer be possible, or a specific piece of software may no longer run, or there may be a cost to stay current, but it’s extremely unusual for a complete capability to disappear.
As I say repeatedly, you can keep using older systems for some time. But at some point, for some reason, you will have to upgrade, and the longer you wait, the more painful that upgrade is going to be. It’s up to everyone to choose whether they want a lot of pain at once, or a small amount of pain on multiple occasions.
Lastly, speaking personally, if I wasn’t excited to see new things from Apple, new apps from our talented developers, and new discoveries and workflows from others in the Apple community, I’d go do something else entirely. We’re all traveling this road together, and if you’re not enjoying yourself, you should switch gears and focus on something you do like. But hey, that’s just me.