Why companies take interview

I am not sure why companies take interviews because if you don't want to take a candidate then why are you wasting their time as well as my time I interviewed 5 times in IQVIA every time they asked me different questions I think I am getting self doubt and getting fear of appearing in an interview . I will not apply to any company going forward as they only want to reject me I am so much stressed and depressed as I am not getting any opportunity to.come out of tcs feeling like I will end my life in tcs.