What does "だがたまには下も見るもんだぜ" mean?

Question

There is a suggestively conversation between two men who are fighting each other. A is claimed to be strongest wizard and B is nearly strong as A. Here is the conversation,

A: 世の中上には上がおる
B: それはよく知ってる。だがたまには下も見るもんだぜ。そいつはすぐ[足下]{あしもと}にいるかもしれねえ。

Here I get,

A: In the world there is (always) upper of upper. (Which implies there is always someone who is stronger than you, OK I got it!!)
B: I know that well. .......................... That guy might be just right under your feet.

Does "だがたまには下も見るもんだぜ" mean "But sometimes there are ones who look down too" or "But sometimes they should look down too" ?? If I'm mistaken then what does it mean? I'm confused about it, yoroshiku onegaishimasu~~

Answer 1

だがたまには下も見るもんだぜ

だがたまには下も見るものだぜ

In this context ～もんだ is a slightly more informal way of saying ～ものだ, which is similar to ～べきだ as covered in this post. So the speaker is trying to say that 'one should...(look down etc.)' For better flow of the translation I would personally translate it as follows:

A: There is always someone above you in this world.

B: I know that well. But you should take a look below you once in a while. That someone below you may be right at your feet.

Hope this helps.