It’s not so much fear they may be next. It’s clearly a hesitance to engagage in a full-scale global war.

I didn't mean to describe it in a light way, at all.

I fully agree with your description that this is a full scale invasion into a sovereign country.

Dutch national news channel NOS had a historian and journalist called Hubert Smeets on. I'm Dutch, and will paraphrase what he said:

Interviewer: "What can the west do, what can the NATO do? It's said that military action is not going to happen, why?"

Smeets: "Very little. The consequences would be very large. This night, in his speech, Putin insinuated how Russia is a global nuclear superpower, and he said that the unthinkable could become thinkable. So that's off the table. All we can do is take economic and political measures; sanctioning, even if we don't know what the effect of these sanctions will be. And turning him into a political pariah, even China said Putin should not pull through on this evasion."

https://www.youtube.com/watch?v=Hm7JiO4tY_Y&t=1036s

So how many nukes did this Saddam guy have? Do you think that can change the calculation?

The ferocity, speed and coordination of the invasion suggest it's not just Putin - this is exactly how a unanimous agreement of all political and military elites look like. Judging from history - we won't hear about the true reasoning behind the invasion and the events preceding it for another 30 years at least