Pentesting related to national security or gov work can pay really well with a clearance (and the workload can be really light). I don't know if the private sector does pentesting pay better than engineering pay.
I found most of the pentesting salaries came in lower than engineering ones, and I felt that pentesting was the more difficult job.
More code results in more bugs. You need to throw money at software developers to build something, anything really. Only then do you hire a 3rd party pen-testing company for a few days. That's the way it works in our shop anyway. It's unfortunate, but sometimes the expected velocity to achieve MVP glosses over best security practices.
I found most of the pentesting salaries came in lower than engineering ones, and I felt that pentesting was the more difficult job.