1)
Why does it say that their makers will be like them?
1.
Radak: This is a Tefilah.
2.
Radak (135:18): So it will be in the future, when Mashi'ach comes; those who make them and trust in them will perish.
2)
Does the verse discuss only those who make them and also trust in them?
1.
Radak: No - it discusses those who make, and those who trust in them. It is as if it says v'Chol Asher Bote'ach. The prefix Vov is omitted also in "Shemesh Yare'ach" (Chabakuk 3:11), "Reuven Shimon" (Shemos 1:2) and similar verses.