Solarpunk

The article is fine, and I second the recommendation to read it, but from the article to the slogan you present, things do not follow a logical path. Yes, war is both an incredibly expensive activity (diverting money that could be used) and a resource-intensive activity (the money goes into actual materials that almost surely destroy something or get destroyed) and an incredibly stupid activity (and it can snowball)...

...but the problem is that successful unilateral disarmament during a war tends to result in a situation called "defeat". If the defeat is not an attack being defeated, but defense being defeated, that is called a "conquest". Now, letting a conquest succeed has a historical tendency of the conqueror having more experience at conquest, and more resources to conquer with... which has, several times in history, lead to another conquest or a whole series of conquests. A regional war in Ukraine resulting in Ukraine being taken over by Russia has a high probability of producing:

1. a bigger regional war later, in which Russia, using its own resources and those of Ukraine, proceeds to another country, gets into a direct conflict with NATO and then indeed there is a risk of a global war

2. an encouraging effect after which China, noting that international cooperation against the agressor was ultimately insufficient, and deeming itself better prepared than Russia, decides that it can take Taiwan with military force

However, a war ending with inability to show victory tends to produce a revolution in the invading country. For example, World War I produced a revolution in Russia and subsequently a revolution in Germany, with several smaller revolutions in between, empires collapsing and a brief bloom of democracy in Europe, before the Great Depression and the rise of fascism ate all the fruits. The Falklands War produced a revolution in Argentina. The Russo-Japanese war produced the 1905 near-revolution in Russia.

It is better for Ukraine to not get conquered. It is better for Russia to be unable to conquer Ukraine. That result is also better for everyone around them. It's even better globally because it sets a precedent of large-scale cooperation defeating an agressive superpower, discouraging agressive superpowers from undertaking similar wars until memory starts fading again.

Unfortunately, until we see indications that Russian society is getting ready to stop the war (this could involve starting negotiations on terms palatable to Ukraine, a change of leadership, a withdrawal, a revolution, etc)... the path to achieving that outcome remains wearing out the agressor: producing enough weapons and delivering them to Ukraine.

Ultimately, both sides in a war wear each other down. The soldiers most eager to fight are killed soonest. The people most unwilling to get mobilized or recruited, and soldiers most unwilling to fight - they remain alive. If they are pressed forever, some day they will make the calculation: there are less troops blocking the way home than in the trenches of the opposing side. After that realization, they eventually tend to mutiny. Invading troops tend to do that a bit easier than defending troops, because they sense less purpose in their activity. In the long run, if nothing else happens, that will happen. There is just (probably, regrettably) no particularly quick shortcut to getting there.