"These guys" held their own against the supposedly second largest army in the world for quite some time before receiving any significant help, and has now, despite all the headlines, regained quite a bit of their own territory which was lost to the Russian invasion, despite the fact that current military technology clearly favours defense over offense (in a scenario without air superiority).

They have also severely depleted the Russian military capability and most likely hindered Russia in invading and bullying their other neighbours for a long time. All for the price of some old hardware that was gathering dust anyway as well as a fraction of a bloated US military budget.

Why did the US support the Allies in early WW2 when France was overrun in 6 weeks and allied convoys got wrecked in the Atlantic?

Ask yourself what the alternative is and what a successful outcome for Russia will enable for Putin! Then ask yourself what that means for Europe. Finally ask yourself what upheaval of a European market will do to an American economy and America’s ability to make its influence felt across the world.

Helping Ukraine is far cheaper.

why is nato helping a country fight russia?

Because it's the right thing to do. Because they're getting invaded by a fascist dictatorship.