Academic here actually working on that part of the world although not a security/foreign policy or Ukraine specialist. First of all, "we" (I assume you mean NATO?) aren't going to war and that's always been clear.
Secondly, its far from clear there is going to be an actual invasion and all this isn't an extremely elaborate bluff, part of hybrid warfare designed to get exactly the reaction it's getting. It's clearly working too, all the discussions about possible concessions.
Important to think about what individual actors actually stand to gain or lose.. Biden and Johnson benefit as it distracts from the prior Afghanistan debacle/Partygate so there's an interest in playing things up. After Kabul, every Western government will implement CYA policies and tell expats to get out, but guess what, China etc haven't done that. In contrast, the Ukrainian government is downplaying the threat because hysteria is not in their interests.
And fourth point.. its not really clear whether any territorial gains would actually be in the Russian interest. Crimea had a huge strategic value for them. In contrast, invading then holding all of Ukraine would take enormous resources Russian can't really afford. As to the Donbass, they'd be crazy to - it's an economic basket case and a subsidies sink and it's no accident they never tried annexation back in 2014/15. What would be much better for them is implementation of the Minsk agreements, with a local puppet government as a substructure of the Ukrainian state able to exercise veto power on Ukrainian central state policies, all the while Ukraine coughs up for pensioners and suchlike. By the same token, Ukraine doesn't really want the Donbass back all that badly but of course, can't ever admit that.
None of that's a guarantee because it assumes people acting from rational self-interest, and the decision-making circles in Moscow have become very narrow and closed so nobody really knows what's going on. But probabilities are still quite different from what our media might make you think.