The motivation should be work. We have moved away from that as being the most important outcome. When I was that age, the vast majority of undergrads saw their degree as a passport to a grad level job with further training. Many were intent on doing better than their parents.,Some didn’t of course and some degrees always were a bit ? However as grads were less common, in general employers were pleased to have them. At the same time the best employers also employed non grads and trained them too.
I think you will find the most sought after courses at Oxbridge are nearer a 10:1 ratio or even worse. Some are nearer 3:1 because there are fewer applicants but also plenty of good ones.
Schools have a crucial role here. Exam grades are not now all you need. Too many have top grades but are one dimensional people. Teachers should talk to pupils about the subject they want and make sure they read beyond the syllabus. Indeed being able to express their thoughts, show initiative and ability to pass the entry tests should be at the forefront when Oxbridge is discussed with pupils. I certainly know of pupils who achieve highly within the confines of the syllabus but do virtually nothing else to ensure they have broadened their education in their chosen subject. I think they can come unstuck when applying to Oxbridge. They won’t elsewhere though.
Schools really should have info about the other universities for the subject the pupil wants. I know it’s very hard for some.
Early applications are closely an indication a DC is going for Oxbridge (excluding a few other early closing dates). In the past it wasn’t uncommon for these DC to receive early rejections from some of their other choices too! That used to cause big problems. Good candidates getting no offers certainly dents confidence.
Oxbridge certainly can help with the chosen career but choosing the best below that level needs schools to be proactive and not lump all other universities as ok. Some are a lot more desirable than others.