Education isn’t just about making money though. A good education can help you navigate through life generally and will give you a much better understanding of how your society works. You’ll find its a lot harder negotiating with lawyers, financiers etc and generally getting things done without an education.
On the economic side of things, I’m not sure how old you are but I’m a definitely older than you and can tell you that what you’ve said is a typical misconception found among many students , namely unrealistic expectations. You think £60 k is a low salary? Go out in the world and try and achieve it, you'll soon see how hard that is
Nobody is going to make the kind of sums that you’re talking about. Only 5% of the population make £85k + so if you are making £65k that is very good indeed, let alone £150k (again, extremely unlikely that anyone is going to do that)
And as for entrepreneurship, two problems with that - 1) not everyone has the aptitude for it and 2) competition and I mean competition from very well-funded organisations. Again, stats show that most (90%) of businesses fail during the first year.
Where I agree with you is that economic practicality and striking a balance between study of its own sake is often lacking in the educational system but be real - a salary of £60K is very good. If anyone is making that, they really shouldn't complain
And education still does generate a better salary than lack of it so economically it still does make sense even if loans as you've correctly suggested have impacted it somewhat
Finally if that salary still isn't enough to buy a house in London, then that's a problem with the way our economy is run and society generally; an individual is not likely to be able to solve that through their own efforts