Shmuel HaNavi gave three long, sharp, Mussar Shmuessin to Klal Yisroel because they asked for a Melech! Asking for a Melech means looking for Hishtadlus [albeit together with Bitachon]. What’s wrong with Hishtadlus? Are we not all into Hishtadlus, by going to work, doctors, etc?
The Malbim says that when a person has Bitachon without Hishtadlus he receives a special Bracha and an Ashrei. When someone has Bitachon only in an Adam, Chas V'shalom, he gets a K'lala. A person needs to keep in mind that despite his Hishtadlus [like going to work, doctors], “success” and “results” are only from Hashem. This is indeed a challenge. When you do Hishtadlus, it is difficult to truly focus on Hashem. So doing Hishtadlus can always be treading on possible K'lala territory.
Don’t make a god out of Hishtadlus. Don’t forget that: בְזֵעַת אַּפֶׁיָך תֹאכַל לֶׁחֶׁם — you will get your Parnasa through Hishtadlus is a K'lala. There is a Ribono Shel Olam in Shamayim, who can help you without any Hishtadlus, in all issues of the world.