I understand the idea that if you’re learning (or for that matter other mitzvot observance) is better here then you shouldn’t make aliyah. But it doesn’t necessarily make sense to think about that in the short term. It may take a while to find a new chavrusa or beis midrash or Rov, but there’s no reason to think that in general one’s learning would be better here.
One might be drafted, but defending the land of Israel is also a mitzvah, and since one cannot come into harm through fulfilling a mitzvah, this shouldn’t concern us either.
In addition, once you are fluent in modern Hebrew, one’s fluency in Biblical/rabbinic Hebrew will also increase. Just think how much more advanced your children’s learning could be if they grow up speaking modern Hebrew fluently. I see it in my own kids’ classes here — the Israeli kids in their school are way ahead because they don’t need to bother with learning how to translate Chumash.