What does "だがたまには下も見るもんだぜ" mean?


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~~




> 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](https://japanese.stackexchange.com/a/6700/1791). 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.




> 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](https://japanese.stackexchange.com/a/6700/1791). 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.

