Has the cost of building software dropped 90%?

The cost of writing simple code has dropped 90%.

If you can reduce a problem to a point where it can be solved by simple code you can get the rest of the solution very quickly.

Reducing a problem to a point where it can be solved with simple code takes a lot of skill and experience and is generally still quite a time-consuming process.

Most code is simple, the fact that large complex systems are layers of simple code on top of itself, like garbage heaps at the dump, makes it complex. Sticking with the garbage analogy, the LLM is like upgrading from one shovel to an crew of 10 people with excavators to look for a lost Bitcoin hard drive.

Your project is still going to fail, but it will fail faster with the 10 excavators.