(from a conversation with KZ)
"Value" is an ambiguous term. Value often refers to both: the "benefit" to the buyer (the theoretical max they are willing to pay), and the amount they actually paid (which is determined by the market). I'll call the first one "benefit" and the second "market price" and avoid the word "value" altogether. The "market price" can't usually go below "cost" to the seller and "benefit" to the seller. AI decreases the "cost" of certain things, thus, decreasing the "price". For some things, easily by 10 to 100x of what it was previously.
For example, AI songs generated by suno.com: for people who listen to music to enjoy it, but don't participate in the social aspects of being a fan... soon, we may end up in a place where an infinite playlist of good music ("good" as judged by someone from 2010) can be generated for pennies per hour, unique to every person (the models will likely be able to create "good" songs, as judged by a collective, but also, "good" tailored to the tastes of an individual). The "benefit" of such a tool is the same as it was in 2010. The "price" has decreased. The "perceived value" of someone making music would likely crater by 10 - 100x, because the "cost" to others has decreased. Music making will still remain as a hobby because it has "benefits" to the participant (it's fun). In the long run, humans won't be necessary in production (and we will all be hobby-pursuers and pleasure-seekers, and politicians).
A plow doesn't change the "benefit" to consumers (they still get wheat). It lowers the "price" for the farmer, and due to competition, the "cost" to the consumer. Without competition, the farmer gets to capture the improvement of the plow as extra profit. A lot of farmers realize that new technology doesn't benefit them, but they are forced by the market to adopt it. Henry George (20th century economist) recognized that even consumers don't really end up benefiting, because every dollar saved on food is a dollar more that owners of land can force their tenants to pay (because land is fixed in supply).