There are several dynamics here.
1) AIs enable knowledge workers to be more efficient. They don't replace them. But they'll get more done. So, you might need fewer of them.
2) This frees people up to do different, more valuable things. There's a scarcity of people on the job market. We have record employment, not unemployment. In short, freeing people up to do valuable things that need doing is a good thing.
3) A lot of the economy is the service economy. It's not about producing goods, or providing essential things like food, health care, etc. Instead it is about providing services to people at some value. The reason the economy has transitioned to that is the industrial revolution. A few hundred years ago, most of the economy was about scraping together enough food for people so they wouldn't starve. That's a solved problem. Farmers use machines instead of dozens of employees. Some of those machines are autonomous.
4) Economies are about value chains and upcycling low value resources to high value services and goods. AIs make certain things cheaper which just frees up spending on more valuable things. What's valuable is determined by people and what they value.
5) If you fire all the people and replace them with AIs (the dystopian view of AI) and they no longer make money. So their spending behavior changes. The economy changes and adapts. Spending just shifts to things we value. Like maybe a human touch.
6) You could argue that much of the economy is already bullshit jobs. Who needs managers, marketing experts, social media influencers, and all the other fluffy jobs that we invent? Somebody values that. That's why that stuff exists.