Why would a scheduled job fail in SQL Developer?

I am trying to create a scheduled job in Oracle SQL Developer that would run once a month and I am testing the Scheduler/Jobs feature where I have created a simple SQL query to test the ability to do this. I have a simple table called "TEST123" and I can see that it works when I do "SELECT * FROM TEST123;".

In SQL Developer I have a Job called "TEST1" which has a PL/SQL Block = "DROP TABLE TEST123;" to run immediately (though I have also tested this with running at a specific time).

After I see that I can still select from this test table and that the STATE of the job name is "FAILED". I left all other settings as default. What am I missing here? Why is it failing and is there a way to fix it?