Wow, I hear you and I definitely feel the same way, especially when the students really are putting in the effort and trying their best.

My mother, who just retired in her mid 80s after decades of teaching nursing gave me a good perspective though. On one hand, she felt very strongly that she could not be too flexible in the standards of her courses because she knew that each graduate had to be able to step into a demanding medical environment where there would be lives on the line. Every year she ended up failing some students that were not able to do the work, but she also kept a folder of notes from former students. Some of those students came back to re-take the course because they really developed a passion for the material, but others realized they were not suited for it but went on to become successful in a different field.

In the end, any course we teach is just a short chapter in a much longer story. We have to do the best job that we can sharing the knowledge that we are passionate about, but we cannot control every outcome.