That one time I did something important
This is the story of the most impactful accomplishment of my career (building Vistaprint's Studio), which happened to be as an individual contributor.
For those of us who've actively chosen to remain active technologists, and have resisted the pressure to join management, it's important to remember that innovation is ultimately driven by individuals.

A commonly accepted notion in software engineering leadership is that managers have a much bigger potential for impact on a business than an individual contributor. This is certainly a credible argument, given that a great manager can have a huge impact through building a great team. They're responsible for recruiting the right people, steering the culture, and making the biggest decisions about what risks to take, what opportunities to pursue, etc. Ultimately, they're accountable for what the team delivers.