That risk doesn't diminish by staying out of the war either.
Ultimately you have a problem with a leader who doesn't recognise the integrity of sovereign status. You have a leader who wants to reclaim the glory of the Soviet Empire and is on record as saying this and has acted by invading another country.
This country had agreements in place which had been fostered by the involvement of other nations. The 2014 Minsk Agreement had been brokered by France and Germany. Breaking such an agreement - and let's stress that there were loud calls for diplomatic solutions steps before a tank went over the border from the US, UK, France and others - represented a disregard for international law.
The involvement of NATO countries and NATO itself having helped train Ukrainian troops since 2014 was well known about. The irony here is that since the fail of the wall there have been efforts to involve Russians with NATO training (something of a legacy from Bosnia and cooperation there)
Now whatever your views on how the US has behaved with international law (and there are question marks), anyone who breaks that is going to be seen as a potential threat and all nations understand this (going back to the US, that does still hold true and its why anti-US imperial sentiments do exist throughout the world).
Given that Russia has nukes, that can't be taken lightly by anyone close to Russia. Especially due to historical contexts and in some cases the fact that freedom had to be fought for in the first place (Eastern Europeans).
The idea that Czech Republic, Slovakia, Poland, Estonia, Latvia and Lithuaniawho joined NATO precisely because of these type of fears would be just fine with it, is one that's nuts. Equally the idea that the US were just going to appease is hard to shift too.
Yet Putin gambled on it because he thought he had the military power to do so. And indeed the West largely thought he had the ability to pull it off and posed a threat and will continue to pose a threat for years.
The point is, is its not about 'not getting involved'. The issue is the moment Russia took sections of Ukraine in 2014 we were already involved and had vested defensive concerns.
No one 'made' Russia do this, no matter what they say. They just didn't. It was a free choice made by Russia.
The war could end tomorrow. All Russia has to do is declare its withdrawal. And thats where it begins and ends in terms of threat of WWIII. In Moscow. Not anywhere else.