Yes, you leave money on the table if you do that (I know I did, I have friends the same age as me who earn a lot more than I do because they went the non-obscure language path early in their career), but at the same time you also bring some purpose into your professional life, which cannot be entirely bought with money.
Or maybe I was the weak one when I didn't see myself programming in something like Java for a living for my entire career (30 to 40 years), again, that would have literally caused me to cry before going to work, in which case, yes, those persons that can surpass that type of feeling should definitely go for the "more money/less interesting programming stuff" route.
By 2016, I knew I didn’t want to be “just a developer”. I enjoyed working with customers, leading projects, mentoring and teaching. But I still wanted to stay hands on
I belatedly discovered “the cloud” and realized I wanted to specialize in true “Devops” bringing developers and operations together and working with companies to show their developers how to be “cloud native” (application modernization)
When $BigTech came calling about a pure software engineer position, I really wasn’t interested. I kept talking to the recruiter and she told me about a cloud consulting position where I would be able to be involved in the full life cycle from pre-sales, to delivering a finished product including infrastructure. I jumped at the chance.
Because of this: "The Python Paradox" [1].
Replace Python (which has become mainstream in the meantime) with any other "weird" language from the article and I think the point still stands.
If it matters I had started learning Python just about when this article was being written/published, and in my early to mid-career that advice of using a "weird" language (Python, at the time) was really good for me, got me into a couple of small companies where I really enjoyed working.
Granted, now I'm already over 40 years of age with a mortgage to pay, I'm a little more flexible when it comes to the technologies being used (even though I would cry myself to work in the early hours of morning were I to use Java, and I'm not kidding), but for people who are quite early in their careers letting them explore and use those "weird" languages will still do them a lot of good in terms of them enjoying their programming work, they might even land on a forum written in Arc.
[1] http://www.paulgraham.com/pypar.html