AI is a new kind of automation.
In the past, people designed machines that reduced the amount of human labour required in a given process. Increased production created economic growth, bringing mode jobs. A high proportion of those losing jobs in one industry/workplace found new ones in another.
AI potentially doesn't just remove human labour from one process. Eventually, it is likely to remove the need for human labour at all. In the immediate term, we are already on the verge of being able to replace a large proportion of the workforce with machines that can do any job those humans are equipped to do, including any new ones that come with economic growth.
Some of those people will be able to retrain to do something that machines can't yet do, but the numbers will grow year on year that can't. If we don't find some way for those people to share in the new economy, then civil unrest is inevitable. The Terminators of the future may not serve a machine intelligence, but rather a ruling human elite.