I started collecting big in early 2000s, basically buying ancients that before never existed, or if they did, were not available in model shops (until then, I only had Praetorians and Anglosaxons, and only other Revell sets were available sometimes). Of WW2 I had plenty, but more or less all factions well represented.
I went on increasing buying all new interesting sets, it was a golden era to every time visiting the shop, new sets coming
. Until I started collecting action figures later, and new interesting soldiers stopped appearing (in my opinion).
Later thanks to my father I had a Napoleonic surge, and been buying sparsely sets since then. The question is, that of ancients, I nearly have all sets that I like, and 95 % of the different armies (I basically lack other versions of the same Greeks, Celts, etc).
The question is that the more you have, the more everything seems like it, and much of the new releases seems to similar to others, and all major topics are covered. Now basically I am lacking some new WW2 sets, but in about 10-15 sets I would have more or less everything I am truly interested in.