We have to discuss this matter on different planes. Your question about bitul Torah indicates an approach that one should occupy himself professionally only with the study and/or teaching of the Torah or some other mitzva.
In fact, the gemara[3] states clearly that a father is commanded to teach his son a vocation; obviously, then, having a vocation is considered positive. The mishna in Avot[4] warns of the danger of learning Torah without taking natural steps to support oneself. (Accepting financial assistance to intensively engage in the important mitzva of study Torah for an extended period without working is beyond our present scope. Indeed, it is problematic to be paid for performing mitzvot.[5]) It is evident from the gemara’s discussion of recommended occupations[6] that they need not be mitzva-related. Rather, they should enable one to live honestly without compromising moral or religious values.
It is important to keep priorities straight and make the study and fulfillment of Torah one’s primary concern qualitatively and, to the degree possible, quantitatively.[7] Few succeed in fulfilling this important directive optimally. However, the failure to achieve perfection does not mandate discarding the system that Chazal foresaw for the average person.
The deterioration of Torah values in Jewish communities throughout the world requires one to make efforts to strengthen his own and his surroundings’ commitment to these sacred values. This includes considering to what extent one’s choice of a profession strengthens not only himself and his family (no small feat) but also other Jews. The most direct way is by choosing some sort of Torah or community related occupation. However, the possibilities for bringing about a kiddush Hashem[8] are vast. The fields one might teach could be of value and open doors for a variety of important contributions. The impression that a God-fearing Jew makes in the eyes of Jewish and non-Jewish students and colleagues can have untold value.
It is unwise for one who does not know your setting, options, and strengths to suggest a field that maximizes the use of your God-given potential. You should discuss the matter with idealistic yet realistic people who know you, and you should give it serious deliberation. In any event, the fields you mentioned need not cause significant problems of halacha or hashkafa.