> I actually do not understand why I would use Racket
You don't HAVE to.
But if you are interested, maybe this would help:
https://beautifulracket.com/appendix/why-racket-why-lisp.htm...
EDIT: Also, if you want a look at the dialects, check out the comic here: http://landoflisp.com/
Be advised that it is extremely difficult to "sell" Lisp and related languages to someone that hasn't bought the idea yet. No-one seems to have found a winning formula. All people see are the parentheses (although, for some reason, they don't see the ocean of []{}(); in other languages).
The normal experience is: you get tired of hearing about all those people preaching about Lisp(or Scheme) and decide to see for yourself. You take the plunge. You slave away at a book or two (or tutorials) trying to grasp the language. And then, at some point, it all just "clicks" into place and you see the light! That's what's its all about!
But then you start trying to explain it to other people... and you have exactly the same problem. All those features you now know about and can't live without? They are either difficult to explain without explaining more concepts, or they just don't see the value compared to what they are used to. "What do you mean, code is data? Code is not data, I use JSON for that."
Which is understandable. After all, if you are writing Scheme, you can easily see the value. You know how Java can spend years (and sometimes over a decade, see lambda) to get a new language feature? Well, with very few exceptions, you can do it yourself. You know 'for each'? A Scheme(or lisp) programmer could solve that in 5 minutes with a macro. But you can't, because you are not a Lisp programmer yet.
Similarly you probably see no problem at all with having YAML with a C program and maybe a scripting language too. Whereas a Lisp programmer would see that as a waste and just want to use S-Expressions for everything. Sometimes including HTML and CSS representation. And maybe more.
But there's an opportunity cost. Up to you if you want to pay for that.
What convinced me and I found it to be true: Lisp or Scheme (and I guess Haskell) _will_ make you a better programmer even if you don't end up using them in your day to day. It will expose you to concepts that you may not be familiar with - or may not had the opportunity to practice.
This is, again, subjective. Up to you. All programming languages are Turing-complete anyway.