GT has a Driver Rating (DR) system. The more people you beat and the better they are, the more you rank up and race against people with higher ratings. DR is therefore an indicator of pace and ability.
Lobbies at Driver Rating D are comprised of drivers who are largely not fast. It is, therefore, not difficult to get lots of very high finishes if you are, in any way, capable.
It's not like the real world where drivers of all abilities race against each other in the same category. DR D lobbies are full of people who are not that fast, or very inconsistent, or don't have that many races completed yet, or who have deliberately tanked their rating in order to race in slow lobbies to get loads of wins.
If you have a "buttload of wins" and you're still in DR D, it suggests that you're not doing it consistently, because your good results are being offset by bad ones.
You shouldn't be in DR D for any more than five races (after the initial five races at DR E) if you have some innate pace and consistency.
That seems unlikely. However mine ought to help you tone down what appears to be braggadocio.
Reset your opinions of yourself and of those trying to help you out - which is what this thread is for. The online world has far, far faster racers than you or I in it.
Incidentally, if you're over 60, why have you entered a birthdate for your GTPlanet account giving you an age of 44?