Karl Marx left it to others to find the way beyond capitalism to a higher form of society. He saw his role as giving them as accurate a theory as he could of how capitalism works, which would also show them the reasons why it needs to be abolished and replaced by a freer and more human form of society.

Freedom is a permanent problem for us, both unavoidable and insoluble.

My own view is that Kant's conception of the duality of the good (morality and happiness, the good of our person and the good of our state or condition) is a distinctively modern view.

Some of Kant's particular moral opinions, either because he shared the prejudices of his time, or because of his own personal crotchets, can strike sensible people as ridiculous or offensive. But in my view, his own theory provides us with the resources (the best resources available, I believe) to correct his own personal errors or cultural prejudices.

What are we to think of the shortsightedness of the great mass of people who are content to do nothing about it, and even worse, the greed or venality of the rich and powerful who deliberately bar the way to human survival?

We can't coherently deny, or even decline to affirm, that we are free.

In the mid-1960s, as hard to believe as it may be now, choosing to go into academic philosophy was not an imprudent career choice. There were lots of academic jobs in philosophy then.