The countries near Russia expect to be next. Part of Germany was under Russian control prior Fall of USSR. Which is why European countries care. NATO has multiple members that are members for this reason. EU has multiple members that see this as an active threat to them.
The USA should care, because they promised protection to Ukraine in exchange of Ukraine getting rid of nuclear arsenal back in nineties. Not that USA would be reliable, but they should not be completely unreliable.
And that USA is member of nato for own interests and that first time there is actual threat to nato they should not ignore it entirely is also fascinatingly ignored argument.
And they surrounding countries taking in refugees is not not particular oddity since surrounding countries always have to take refugees when aggressor goes in is also ignored argument.
If you're in any country but Ukraine think about WHY you're picking sides and who told you to do that.