Definitions from Oxford Languages

rad·i·cal /ˈradək(ə)l/

adjective

1. (especially of change or action) relating to or affecting the fundamental nature of something; far-reaching or thorough.

2. advocating or based on thorough or complete political or social change; representing or supporting an extreme or progressive section of a political party.

noun

1. a person who advocates thorough or complete political or social reform; a member of a political party or part of a party pursuing such aims.

Now that I've made sure to include the definition of radical and we've already established that anarchy is not a political party, look and see why being radical or being a radical is demonized. Being radical is literally being through and attacking the issue at the root, "affecting the fundamental nature of something." Capitalists don't want people to be radical leftists because being radical is being effective. Instead, they want people who will maintain the status quo and if they complain, they can at least be pacified.