"Gradually, then suddenly." ― Ernest Hemingway, The Sun Also Rises - One of my favorite quotes from his works.
It's about going bankrupt, but it applies to a lot of things - including nations.
At the time sanctions were imposed, I thought expectations were vastly overinflated in the West regarding people rising up due to privation. But sanctions were a necessary part of hampering the Russian war industry.
Imagine the situation if Russia still had a vast influx of money (mostly Deutchmarks) while the war continued. Not saying that Ukraine would have folded, but it certainly would be more dire.