You start interviewing and you see that none of the above happens 99% of the time. You wasted 2 years learning a bunch of stuff when you really should have been

You start interviewing and you see that none of the above happens 99% of the time. You wasted 2 years learning a bunch of stuff when you really should have been interviewing six months after writing your first line of code. I agree with this. I have interviewed a good amount of engineers, both as a SWE at Google as well as founder of my own company. From that experience I can tell that the only thing that asking mostly hard interview questions does is reducing your candidate pool to 0. Even with mostly moderately hard questions your candidate pool at the end of the funnel is probably going to be around 5% to 10% as compared to the start of the funnel. Plus after a certain level of question difficulty as an employer you're probably optimizing for the wrong skillset. Perhaps for super competitive positions, e.g. for algorithmic trading at reputable Wall Street hedge funds, there's a place for killer interview questions but it's definitely not the bread and butter.