In all post-Soviet countries they will tell you "Nas Mnogo" (lit. "there's a lot of us") is THE Russian strategy. It used to sound scary when we thought manpower is everything. Today, with drones and things like Javelin... Seems more funny than anything else.

I think it still sounds scary, as in a scary disrespect for human life

Agreed 100%, I never understood Russians themselves using it and being proud of it.

Do you think it seems "more funny" to the grieving relatives of dead Ukrainian and Russian sons?

No, but it wasn't uncommon to have pro-Putin/pro-Soviet Russians tell you this phrase on the street (I live in CZ) - as an insult/threat, usually the next sentence was something like "Czechia belongs to us too and we will soon return". That's what would sound very funny now, especially if they delivered it in the usual manner (drunk rage).

From the military perspective, in a morbid sense - yes.