This counter-offensive looks like a last-ditch, long-odds gamble to try and flip the script somehow. It makes sense for Ukraine because:
- If they stay the course, they lose;
- The only other game changing strategy -- turning this into a broader regional war with other countries attacking Russia -- was tried and has failed; and
- They can't negotiate with Russia due to fascists in their ranks and the veto power their NATO allies wield.
It's throwing up a desperation shot from the other side of the floor at the end of a basketball game. Of course it didn't work, but of course they tried it.