As with many metaphysical and religious questions, Kant thinks they lie beyond our power to answer them. If you can't stand the frustration involved in accepting this, and insist on finding some more stable position which affords you peace of mind and intellectual self-complacency, then you will find Kant's position "problematic" in the sense that you can't bring yourself to accept it. You may try to kid yourself into accepting either some naturalistic deflationary answer to the problem or some dishonest supernaturalist answer.

I think the contribution people make is not proportionate to their fame or success. In fact, I think the relation is often inverse.

There is no author or legislator of the moral law. It is simply valid in itself in the nature or essence of things. We become autonomous only when we obey it, because then our will aligns itself with the objectively valid law, and our choice follows the same law as that we give ourselves. We can think of rational faculty (or the idea - the pure rational concept, not exhibitable in experience) as the legislator or author of the law because reason recognizes an objective standard, and to that extent is already aligned with objective moral truth.

People who enjoy the privileges of success must use these privileges to benefit those who do not have them. These privileges constitute a deep hole they need to climb out of if they are to prevent its being the case that the world would have been better off if they had never been born.

Leaders of nations, and people whose wealth or fame gives them power over the lives of others quite often do more harm than good.

I think the term "Kantian constructivism" as an oxymoron. Kant was a constructivist about mathematics, but not about ethics.

Not only our moral life, but even our use of theoretical reason - on which we rely in rationally inquiring into nature - presupposes that we are free.