I also can’t accept this concept that ‘Hashem will provide as long as I have done my hishtadlus in trying to earn a living’ but then you turn around & do a substandard hishtadlus in trying to earn that living. Yes, our hishtadlus has to be based on the facts of life that Hashem has set up for us and not doing so means that you’re doing a substandard hishtadlus.
Another mashal (I know you may not agree but it’s still useful to illustrate the point) – A person is not allowed to say that I’m doing my hishtadlus by taking my medication once in a while and it’s up to Hashem to take care of me from there. You have to truly do your full, proper hishtadlus. It’s interesting – let’s draw from Rambam. He certainly did get a proper education in both secular & Jewish studies. He provided medical advice to his patients knowing full well that it’s really Hashem that will heal them, not the medication or treatment. None-the-less, it was his job to fully abide by the rules of healthcare known to him at that time and it was the job of the patients to truly follow through on the treatment. Only then could both doctor and patient say they did their fullest hishtadlus and feel good knowing that
Hashem will then take care of them.