culbuter

Culbuter means to tumble or topple over, and figuratively, to knock over or rout an opponent — an obstacle, a rival, or an established power (culbuter les traditions, culbuter l'ennemi in a military sense). It's a physical, forceful word.

• L'enfant a culbuté en bas des escaliers. — The child tumbled down the stairs.
• L'armée a culbuté les positions ennemies. — The army routed the enemy positions.
• Ce scandale a culbuté le gouvernement en place. — This scandal toppled the government in power.

Culbuter implies a sudden, forceful overturning — not a slow decline — so using it for a gradual loss (a business slowly failing over years) doesn't fit; it's the right word for a sudden fall, defeat, or overthrow, not a gradual one.