At the time, Rockefeller (Standard Oil) had his own private police force that would beat up workers (i.e. kill) who helped other oil companies and also blow up their train tracks. He said this was fair competition. Take into account the sugar, steel, train, banking, and other monopolies and it was a racket.
Roosevelt focused on getting it to be a fair playing field.
Put into the mix novels such as The Jungle and it is a ripe time for an uprising. What we see today is similar which is people angry at the status quo. They see corruption at all levels.
There are some on this thread who bash TR when they don’t have an appreciation for American history as their family were still in other countries when TR was President.
My great great grandfather was in New York City politics when TR was Gov. on NY and major Republican.