First questions, my first job after CPF deductions paid me SGD 1,999, and I was a direct honours graduate. That was quite a few years ago though, so I’m not sure what entry-level pay is like now.
Secondly, on staying or leaving a job you dislike: If you have thick skin and can mentally endure it, then it’s best to stay until you find a new job. As a general rule of thumb, don’t resign unless you’ve already secured something else, but if the job is already affecting your mental health, then it’s not worth it. Walk away if you need to.
About PIP (Performance Improvement Plans): Usually, being placed on a PIP, in my opinion means they already want you out. So if you are on one, it’s a sign to start looking elsewhere, and preferably resign before you get terminated. In my experience, if your boss genuinely wanted to help, you would not be on a PIP to begin with. Most people only end up on a PIP if their performance is really not up to par. For sales roles, it can happen more easily if you’re not bringing in results.