Lysosome is considered as suicidal bag because

The lysosome is considered a suicidal bag because it causes autolysis of the cells.
Lysosomes are membrane-enclosed organelles that contain an array of enzymes capable of breaking down all types of biological polymers-proteins, nucleic acids, carbohydrates and lipids.
They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules, and can cause autolysis of the cells.