With a sharp knife, you cut through food very easily so you use very little force. You also use techniques that prevent you from getting hurt, such as the claw ( https://www.thekitchn.com/knife-skills-the-claw-75998 ).

But if someone has used a dull knife for most of their life, they may not have cultivated these skills and may hold their knife in an unsafe way and or use a lot of force when cutting.

For someone like that, a sharp knife could be a lot more dangerous, but if they're trained/using it properly, a sharp knife is a lot more safe as it reduces effort and chance of the knife slipping.