I know of quite a few others with collections that range in the 600 to over 1000 range.
All who hang out here, all who respect everyone else's collection.
Some collect by brand;
others by complication.
Some collect by "horological significance" and others purely by what "tugs their heartstrings"
Some for representative examples of regional styles.
I myself have collected along all these modalities; I've found my fascination is along how a particular piece "represents" something - a particularly good (or bad) repeater; the smallest tourbillon and the largest; differing "periods" for a brand that I particularly like (mostly AP)
In the end, I get what I like, even if it doesn't qualify for a "category."
And I fairly regularly "rotate" the crop - wear any and all, and de-accession one (or more) when a better specimen or representation comes along.
Conceptually, I agree there is a distinction between "acquiring" and "collecting" but in practice, it is pretty hard to be rigourous about it, and most just end up fitting a justification around something they really like.
Cheers,
TM