Why is GCP cloud scheduler so expensive?

As mentioned in the doc here:

The actual running of a job is called an execution. A job is not billed for individual executions. For instance, if a single job is defined to run for "every day of the month", then that job is billed $0.1/month and not $3/month for 30 executions of that single job.

So if you have only one job running every hour for 6 months, you'll be charged only $0.60

regarding:

The pricings only apply on the 4th scheduled job set and beyond. The first 3 are free. – Kolban Jul 23 '19 at 21:28

its important to know that its per account not projects. So if in one google account you have multiple projects and in each of them 3 jobs - only 3 jobs in all this projects will be free.