The west is dangerous as hell, they've really sacrificed Ukraine to weaken an opponent and masters of proxy warfare. Those Javelins and NLAW's are super dangerous. Guess anyone will think twice before going up against them again, but sacrificing Ukraine shows a dangerous lack of long term planning among western leaders.
And Russia has taken a huge territory so far. That's massive, for a week.
If losses are as high as stated by the Ukrainians, or even close to being that high, the amount of territory they have taken is negligible. Urban warfare is next, and if they decide to level every Ukrainian city like Grozny, not only will that take quite a long time but also a ton of supplies. I believe if the Russians do start an indiscriminate, large-scale artillery campaign of urban environments, which will only fuel a bigger insurgency that could very well disrupt backline logistics.
The further into Ukraine they go, the longer their supply lines.
Keep in mind the U.S lost 196 men in the 2003 invasion of Iraq, which lasted just under a month.