I made the move from smaller startups to progressively large companies and from IC to manager. My main motivator is to continue to find personal growth, which increasingly means learning about the human side of building software at scale. As I approach 50, a bigger pay check and more stability are of course bonuses, but I find the idea of software engineers "retiring" at 40 pretty offensive. It reeks of entitled rest-and-vest culture, and will put you in a position where companies would be right not to hire you. Instead, stay hungry, and find a place that rewards that.