Should high school education be mandatory?

I propose that it is unnecessary at best, and a complete waste of time at worst. For one thing, most of what is learned in high school is forgotten in adulthood, due to sheer lack of use. For another, the large amounts of time spent in high school could be spent learning a practical trade or doing an apprenticeship. For those with keen interests, high school could remain an OPTION, much as university is now, and the environment would probably be more conducive to learning when it is not forced on the entire populace. Many kids are simply not suited to learning from books in classrooms for hours a day and could be learning in other ways, from family and friends, from the community at large. It is understandable that for young kids without a supportive family, compulsory education would help them, but I think beyond the age of around 15 it stops being a benefit for some and becomes a cumbersome duty, which they do simply not to fall behind. And it would help society at large; what is happening now is a strange distortion of the skilled workforce - more people are educated but are finding it harder to find specialized work because of the increased competition. Should high school become optional, the pressure would be reduced and true market forces could work to bring out the most suitable to such positions (ie. those with the aptitude AND interest). Also, it goes without saying that many people don't complete high school; the investments made to their high school education are therefore wasted. This money could be redirected to support alternative options.