I couldn't be living with all that debt to stay on at school. For me that was at least 3 years head start on anyone staying on, and accumulting by the year. Imagine people that stay in the system learning until they are in their mid-twenties, that's a whole decade. Yeah the latter would get a good wage at the end of it, but wasn't for me. I enjoy learning now I'm older, but just didn't have the concentration when I was younger, well my brain still switches off at times now, but with old age and slowing down, not everything is such a rush in life.
Everything has its place imo. Leave studies at 16 or go on I don't see a problem. Some degrees are a waste of time, but others in worthwhile professions you need to be there into your mid-twenties to gain the skills and knowledge to do the job, like if you're looking to be a doctor, an architect or aeronautical engineer for example. Most leave university by 22 though and those staying to 23 usually have a year out in industry which is a good thing. Apprenticeships is becoming huge and a good alternative to degrees with a lot of employers coming on board to work with schools as a pathway into a wide range of industries.
