First movers rarely win markets in technology. Ramp is a real competitor to Brex. DoorDash was founded years after GrubHub, Seamless, and Postmates. We use Excel instead of Lotus (or Visicalc). Facebook beat Myspace (and Instagram "beat" Facebook).
When Google was founded in 1998, there were at least 20 other venture funded search engines. Google wasn't even the first to do pay-per-click advertising on its search engine either (that was Goto.com).
Why is fast following so effective? Fast followers can short-circuit the learning curve that the first mover took so long to discover.
First movers painstakingly discover product market fit – through costly experiments that generate technical and organizational debt. The vast majority of these learnings are observable by potential competitors: APIs can be copied, discovered markets can be entered, and marketing can be emulated.