Many moons ago I heard these lines:

  - "Just when you think you're the smartest, know that there's someone out there that's just as smart and probably ten times smarter!"
  - "There's no such thing as an expert"

Loss of morale is what undermines the persistant efforts needed to make great things happen.

Having a healthy ego and doing objectively great things to feel good is not in itself 'toxicity' that must be 'killed'.