Emotionally, because I'm not a sociopath.
Politically, because whilst Ukraine isn't a NATO state, Putin's vision of empire doesn't stop at Ukraine. And if he crosses the border into a NATO state, it's war, full stop.
Economically, because it's going to play havoc with prices at a time when the world is still reeling from Covid disruptions and before they've figured out energy.
Strategically, because not being able to stop him is a step back in power for Europe and the West, which has already been accelerated due to Brexit and the nativist policies that have eroded support for things like NATO and the EU.
Prognosticatorily, because if China decides that they're going after Taiwan as Russia went after Ukraine, we're directly dragged into a Pacific war as well.
And culturally, I suspect some of the shock writ large is because Ukraine is familiar to so many in the UK. That's not a good reason (and it's quite possibly a problematic one, at least comparatively), but one of the reasons you're seeing shock is because people regularly travel to Ukraine, because they're on bloody Eurovision (cf Verka Serduchka) and in the Euros, and are culturally familiar across the UK.
Also, again: not a sociopath.