If only 10% of people who enter any program (and who are selected based on criteria set up by the leadership of that program) complete the program, IMHO, there's a problem with the program.
In my day, roughly 25% of each USNA entering class attrited. The Navy realized they were spending a lot of money, time and human effort to attract the right and "best" candidates -- losing 25% of them didn't seem to make sense. So, they tweaked the program to provide more support to mids (especially with academics). Some would say they made the program easier. I don't think so, but the model has changed from: "If you fail (leave), you weren't tough / strong /smart enough," to "If you want to be here, we'll help you succeed."
Losing 90% (or even 60%) of SEAL candidates seems a huge waste of time and effort in the training program and makes one wonder if they have the proper selection criteria up front. Also makes one wonder if the SEALS are attriting people for the sake of exclusivity vs. what they really need in a good SEAL.
If the reports of drug use are true (not saying they are), that would be concerning. If you can't get through training without PEDs, are you going to be able to get through your missions w/o them? And do we want folks with PEDs in their system participating in or leading those missions?