When I started programming professionally (post dotcom crash mid-2000s) you could really achieve results that were considered game-changing for businesses as a solo contributor writing all your own code from the ground up. The field as a whole had not been really mapped out all the way, so even someone of moderate intelligence like me could feel like they were creating new useful things (especially on the web).
Modern software development frequently feels like gluing together towers of shit from other people's towers of shit. Additionally, the parts of the industry where the business case is "a computer could markedly improve this process and make people's lives so much easier" are pretty much saturated. The high paying career opportunities that are left generally seem to trend towards either value extraction or rent-seeking behavior.