Western observers and analysts greatly overestimated the effect sanctions would have on the ability of the Russian economy to keep functioning. Many predicted that the Russian economy would quickly descend into chaos with sectors relying on western tech more or less ceasing to function. They were wrong.
I don't recall reading any economists predicting the Russian economy would collapse in a couple of weeks after sanctions were imposed.
Three years after sanctions were applied, some sectors may have more or less ceased to function. The extreme example: production of airliners fell to zero in 2024 and (when I last checked) one so far in 2025. Do Russians really believe Putin's assurance that Russia will produce a thousand new Russian airliners by 2030? Do Russians know that at the rate of progress shown since the invasion, it will take around 4 more years to occupy the rest of Zaporitzia? Putin is prepared to accept high manpower losses but would he be able to cope with several hundred thousand more casualties to occupy the rest of that oblast? By the way, British intelligence is reported to put the number far higher - more like two million.