Most like because they thought Ukraine was going to capitulate in few days, and they could hide the crimes of genocide, like it was done in the past.
That's how sickening this was, because Russia thought they were going to get away with it, they were just executing civilians for fun.
The whole world watched this in real time.
It's evil in at it's worst, for some sick illusion of ethnic superiority.
History will not forget this.
These are people going into a neighboring country that posed no threat to them, or to their way of living, to make money killing what many deem an inferior ethnic group.
Couldn't they choose not to go? Don't they have family members? Friends?
Just because some don't want to have anything to do with it, they're still paying taxes, funding the war, they're part of the economy that supports it.
Going about their lives with head down is being part of the problem.