This is probably one of the most understated, horrifying scenes in the show. Thief King Bakura is fully conscious as he turns into sand and collapses under his own weight, is mocked by Yami Bakura as a pawn (he even treats his past self like dirt), and he has no idea what’s been going on up to this point.

I think what really makes it is him screaming for help about 2 seconds before he dies.

Remember that time Romana learned everything there is to know about Earth in about 45 minutes?