How (in-)formal is it to say to "become/get hooked on/by something"? Are there differences in meaning?

Question

I'm currently working on an application for a summer school and would like to say:

When I heard that understanding X required something called Y, I immediately bought a book on this topic, only to later become hooked by Y itself.

(Both X and Y are placeholders for scientific fields)

Question 1: Is this too informal?

Moreover, I'm starting to wonder in how far the verb and the preposition matter here: Most dictionaries seem to suggest get hooked on something. but I went for the above combination of verb and preposition because:

1. In formal situations, I subconsciously tend to avoid get in favor of become. (This answer here seems to agree with this choice.)
2. For me, the preposition "on" somewhat implies excessiveness or even has a connotation of uncontrollable drug or substance abuse, neither of which is the meaning I'm trying to capture here of course.

But, as usual, the more one ponders the words, the more one starts to question their meaning… So I'd like to add some follow-up questions:

Question 2: Is it actually possible or common to say become hooked by something. in the first place? Mr Lister has pointed out in the comments that hooked by can have a totally different meaning, though a quick Google search suggests that this only seems to be the case for get hooked by. In contrast, become hooked by – despite the fact that it produces only a few thousand results (and that it can't compete with the get variant on Google Ngram) – seems to be used exclusively in a non-drug context and with pretty much precisely the meaning I'm intending. Example:

I first read the paper as a final-year undergraduate student; I had become hooked by the study of behaviour and particularly fascinated by the evolution of animal signals.

-- Candy Rowe: Receiver psychology: a receiver's perspective. In: Animal Behaviour, Volume 85, Issue 3, March 2013, Pages 517-523 (link containing quote)

Example 2:

But traveling great distances is not uncommon for competitors who have become hooked by a sport that most people see only when the Winter Olympics roll around every four years. (source)

Question 3: Does get/become hooked on indeed imply excessiveness?

I apologize for asking three questions at once. I couldn't quite disentangle them to post three separate questions.

Finally, I'd very much appreciate suggestions in the comments for an alternative, formal expression for become hooked by, should the answers to the above questions mandate one.

Answer 1

Even Oxford dictionary seems to agree that hooked in that context is woefully informal, even slangy. I'm sure Urban Dictionary had a field day with it. Your intent seems to be striving for some formality with the application, and I expect that you're hoping to be accepted based on that. So I would suggest something along these lines:

When I heard that understanding X required something called Y, I immediately bought a book on this mysterious topic, only to find Y itself equally [or more] interesting.