Actually the members of the Sanhedrin were required to have a lot of secular knowledge.
ONLY the Sanhedrin (etc.) learnt that as they required that knowledge. The hamon hoam did NOT study these secular subjects.
The Chasam Sofer in Parsha Beshalach states clearly that certain secular knowledge is useful for learning certain Torah topics, such as cow anatomy being useful for shechitah, and arithmetic for Eruvin and Sukkah. But that before we embark on obtaining secular knowledge – and of course that means only to the extent that it is useful for our Torah studies – we must first fill ourselves with Torah-only knowledge. After we are strong in Torah, only then can we move to acquire the useful secular knowledge that we need for our Torah studies.
He quotes the Rambam, who he describes as “the father of philosophy” in our religion, in Hilchos Yesodei HaTorah, stating that a person may not learn philosophy until after he has “filled his stomach” with Shas and Poskim, which are the things, and only the things, that bring us Olam Habah. Then he quotes the Rashba, saying that there is a cherem against learning any secular studies if you are under age 25! The he quotes the Gemora in Brachos “Keep your children away from science” (higayon, as some meforshim translate it), noting that the Gemora is directing its prohibition at “your children”, but not at the adults, for adults, who are already advanced in Torah knowledge, need some secular knowledge, such as cow biology (I keep emphasizing that so that we do not make the error of thinking that the secular knowledge that we need is a college education). But it is dangerous for us to pursue it until we are armed and ready with a Torah foundation. This is because someone with a Torah perspective looks at the value and culture of of secular studies differently than does someone ignorant of Torah. And we do want to get the proper perspective.
It’s kind of like firemen putting out a fire. They have to (a) dress in their heat-resistant protective outfits, and (b) run into the fire and put it out. But of course, they have to do it in the right order.
And that is indeed what it boils down to – do we value the Torah’s standards of education more than that of the secular world or vice versa? The choice is simple: All the secular “education” that you get will be useless to you in the next world. There, they will not ask you if you know how many US presidents were re-elected in history, or whether you are familiar with the policies of Chairman Mao, or if you know how to program a computer. They will bring a Sefer Torah scroll to you and ask “do you know what it says in here?” The more you know of that, the more you will be considered “educated”. The less you know, the more you will be considered ignorant. So the question is – do I want to be educated on this world or on the next?
And please note, there is no minimum threshold for the amount of Torah you are obligated to know. The rule is: more is better; less is worse. And the difference between just a little more and a little less is staggering. As the Vilna Gaon points out, one word of Torah knowledge gives you more holiness than an entire lifetime’s worth of doing other Mitzvos.
And here we thought that a secular education is expensive! Its much more expensive than you think – you can acquire it only at the expense of your time and effort that you could have been putting toward becoming educated in Olam Habah.