This is just a list of grievances and false accusations

What you just read was a gently formulated history lesson, from a person who is far closer to the situation and far better informed, yet has no obligation to teach you history.

If your actual position is “I don’t care about facts, I don’t care about justice, I just fear World War 3”, you should be sincere about it. Fearing war is understandable, but you should then say that.

In the early stages of World War 2, people also feared war - so badly that they let dictators have parts of countries, then entire countries. In the end, what came out of it - at first they got shame (for failing to help allies, for persuading victims of agression not to resist - for being fools of the greatest variety) and then they got the biggest war in history, because an appeased dictator generally doesn’t stop. He’ll consider it a sign of weakness and try harder.

An important element in your views appears to be “I don’t need Ukraine”. Correct, an individual does not “need” a country - I don’t need any country in the world.

States do need alliances to safeguard their interests. Alliances are easier to maintain with societies that work similarly. States do develop relations of trust, and occasionally give each other access to valuable resources or knowledge. Betraying trust is considered a bad thing, since other partners stop trusting you then. Simple game theory, OK.

Ukraine received a promise in return for giving away hundreds of nuclear warheads: https://en.wikipedia.org/wiki/Budapest_Memorandum

The three memoranda were originally signed by three nuclear powers: Russia, the United States and the United Kingdom.[1] China and France gave somewhat weaker individual assurances in separate documents.[2]

The memoranda, signed in Patria Hall at the Budapest Convention Center with US Ambassador Donald M. Blinken amongst others in attendance,[3] prohibited Russia, the United States and the United Kingdom from threatening or using military force or economic coercion against Ukraine, Belarus, and Kazakhstan, “except in self-defence or otherwise in accordance with the Charter of the United Nations.” As a result of other agreements and the memorandum, between 1993 and 1996, Belarus, Kazakhstan and Ukraine gave up their nuclear weapons.[4][5]

…but now that Russia has violated the terms of the agreement, other countries have to uphold their part of the deal. Many do because of their sense of justice - because they have a vested interest in preserving a rules-based international order. Others do it because they are likely candidates for Russian invasion.

The US helps Ukraine in the war because it has a vested interest in global stability. To demonstrate that international law applies, countries have to act when law gets violated. Deterrence was tried in autumn 2021, but sadly it failed. Now, for already 1000 days, weapons must back up ink on paper, showing that international law still applies (and violations have consequences).

If the US ignores its promise, allies of the US know that the US will ignore promises when not convenient. The network of alliances in Europe and Asia which gives the US a considerable extra layer of safety - it will come loose. Stability will be weakened, new conflicts may start. If someone thinks of attacking the US, they will no longer compute the numbers for fighting countries inhabited by a billion people, but only those who bother.

You mentioned Taiwan, and said you considered Taiwan unlikely to withstand Chinese attack. China is watching the war in Ukraine very attentively. If other countries assist Ukraine “no matter what”, China may consider it smarter to wait another 100 years for peaceful re-unification (if it ever comes) rather than attack Taiwan, because “no matter what” is a very high price.