They wanted to destroy Russia economically, not militarily, you know, the usual "bog them in forever war and sanction them to death because we control the world finance systems" and it had a good chance of success, but they miscalculated since Russia relations with China and global south in general proven to be much more robust. It was also first time after 1991 so many countries just told US "no" when they demanded another country be destroyed economically. As result BRICS managed to build their own alternative for US controlled finance system, which is pretty ad hoc by now, but it already works and is being strenghtened.

The west has to balance providing adequate arms and not getting bombed/invaded themselves. They only do invasions on enemies they think can't defend themselves.

They thought the sanctions would do to Russia what it did to Libya, Venezuela, Iraq, and many others, and that they'd only need to drag this one out to win it on the economic rather than the military front. That obviously hasn't worked, so rather than broker the peace talks a majority of Ukrainians want, they're escalating because they don't know how to do diplomacy, they only know how to do extortion. They're talking about "negotiating from strength" ffs.