Learn
The phrase “make good money” refers to earning a high salary. This is most often used for someone who would be considered upper-middle-class, a person who works in a job.
We would not use this to talk about someone who has a lot of investment income or who has gotten money from the sale of a business or an inheritance.
“She makes good money at her new job” means that she earns a high salary from a job. “He makes good money from DJ-ing at weddings” means that he gets paid well for being the DJ at weddings.
The important thing is that the income is considered high (for the situation) and that the person actively works for the money.
In today’s story, you heard that Twitch streamers can make good money. That means, it’s possible to make a high income from being a Twitch streamer. But as you heard today, those are the exceptions.