In the older type of Torah system it was considered that learning Torah is the highest mitzvah and that as much time one needed to spend on a vocation was acceptable but not desirable.
Now the Rambam is probably the best support of Torah of all. He is highly rigorous but leans towards Aristotle.
So between the Rambam the Ramchal there is fairly strong basis for Torah.
So the lack of a basis is not what is bothering me. Torah has great intellectual and moral validity, but it does require some effort to discover what it is and how to live in accordance with it.