I'm not necessarily disagreeing with you but in my experience, the more I understood math, the less abstract everything became and the more I saw that everything is connected and at it's base, is a math problem.
Maybe I don't understand the word "abstract" here.
abstract just means it only exists in your head
take for example 2 + 3, = 5. this is arithmetic, arithmetic exists on 2 levels, abstract and concrete. If I want to show it in a concrete way, I take 2 apples and 3 apples and put them together and recount them. You can see and feel what 2+ 3 = 5 means. but 2 + 3 is also a an abstract concept, in the sense that you can take 2 of anything plus 3 off anything (lets say galaxies) and have 5 and do this in your head
but what if I say what is the square root of 2 + the square root of 3? there is nowhere in the universe that you can point and say 'there is the square root of 2" , meaning square roots are abstract, they only exist in your head
you can apply square roots to the real world but ultimately the concept of the square root only exists in your head, having the power to manipulate that abstract concept gives you the power to apply it in the concrete world. which is why math is so powerful
So I think what you mean is that as you learned more math you saw how to APPLY math to the real world, but in the end the mathematical concepts and models themselves only exist in your head ie abstract
the other important part of abstract thinking is that it allows you to extrapolate new information and come up with things that did not exist before, these extrapolations are more abstractions. So going higher in math is really about abstractions built on other abstractions