It's always interesting reading thread like this, resonating with others' view on the hobby of choice, collecting experience and moving forward. Will find the time to read up all the replies.
If i recall correctly, it first hit me in 2014 (turning 30) that "hey, you are an adult now - need to start making rational financial decision", but nothing changed until the discussion of schooling for my son came up and I realization that the yearly tuition fee is almost a quarter of my annual income and will continue to be so for the next 20Y (that's how it is here - private school is the preferred route to go). He started school last week.
Fortunately, I have never been fully invested in any franchise/story (except Metal Gear) and I only collect figurines - so even when I'm buying what I like, it has never gotten out of hand. I have approximately 40ish 1/6 figures and 5 statues. I skipped HT-Batman (DKR), HT-Alien, HT-Iron Patriot, Verycool-Mai and will probably be skipping a lot more figures this year. Also selling off some of what I have (e.g. Worldbox-Kratos, TE-Vulture, Iconiq-Ryu, and will do so for Lim-Drake soon).
I don't really have an end-game. May be it'll happen the same way my gaming life "more or less" ended, without realizing, that one day was the last time I powered on my PlayStation.