If you want a silver bullet for success, go to an ivy league or similarly-pedigreed school. There are plenty of people graduating from the top schools that burn out on their programs, but still get into successful gigs based on the reputation of their degree, and the connections they made.
Didn't study hard in high school, or Mommy And Daddy didn't send you to private school? Too bad. Life is competitive, and it needs to be that way if we want to make progress as a species.
No one is saying failure should come with punishments like unemployment or homelessness, but not every program out there needs to be as easy to coast through with C's as Harvard is. Not everyone needs to be a developer, doctor, pilot, etc., either. But the military needs almost everyone to get through boot camp.
I am fine with the programs being hard. But these programs should only accept students who are likely to make it through. If they create a hard program but take anybody who can write a check, then it's a badly run school.
I hope you can see how the above disagreements are still related... It seems self-evident, no?
In my limited experience, the ones that struggled most were the ones who simply didn't do the prework that was asked of them. Some people think education is something that will happen to them if they pay somebody enough, compared to those that went to a boot camp to accelerate the self-education they had already started.
If plenty of folks enter a boot camp and wash out because they aren't prepared, I don't think that's much about the students. I think that's a huge failure on the part of the boot camp program.
The theory of boot camps is that you turn anybody who qualifies into somebody basically competent. E.g., US military boot camp drop out rates are around 10%. If ill-specified student quality is used to justify higher failure rates, then we end up with something almost tautological: only the quality students succeed, and the way you measure quality is by whether or not they succeeded.