Everyone is different. We each have a different budget, and different lifestyle. As well as a different climate. (For some, jeans are an all-year item; for others, they are only useful in specific seasons).
I am probably not a great example here. I work from home, where I curl up on a couch with my laptop more often than I sit at an actual desk. I live in a casual city. My style is more androgynous than ladylike (though I do have a ladylike streak). I travel frequently by train (which can be dirty and requires clothing that launders easily.) I walk a lot. And I live in a 4 season climate. As a result, I wear denim almost every day in spring/ fall/ winter. And denim shorts in summer.
I have a jean collection that many would consider excessive: 14 pairs. Is it excessive for me? It seems not. Technically, it is more than I *need* of course. But it's not a wasteful collection. I have been tracking wears. My least worn pair (a 4 year old pair of flares) has had two outings since late September. My most worn pairs have had more than 20 outings each in the same period. And note I said pairs, plural. CPW goes down pretty quickly when an item is getting that much use.
What abc says about cut, fabrication, etc. is pertinent. Some of my jeans function more like "casual pants" than like blue jeans, per se.
The jeans I own are the following:
BF and slouchy: 4
TR Cameron BF jeans (dark wash, all cotton, back flap pockets)
BR slouchy skinnies (5 years old, distressed wash)
Rag & Bone BF (lighter wash, more like a slouchy skinny fit)
Gap original fit (dark wash, rescued from daughter's donate pile, all cotton)
Skinny: 6
Kut white skinnies (mid-low rise -- mostly warm weather use)
Cream BR jeans
CoH Racer Patina (mid blue wash, lower rise)
CoH Racer taupe (low rise)
Plaid Kuts (PATTERN -- not a true winter jean)
Grey GAP
Legging type jeans: 3
Bleulab reversible legging (winter wear only)
DL 1961 dark legging (winter only)
Dark plaid Kuts (winter only, PATTERN)
Flares: 1
Long & Lean bootcut (good weather only)
You can see that these have different purposes for me and don't all get worn at the same time of year. I tend to wear BF jeans most in spring and fall and on cooler summer evenings. I wear my skinnies more in winter. I wear my legging jeans
ONLY in winter. I wear my flares on the rare days with great weather when I am going to be out and about more than at home (they are a pain in the house because they are hemmed for heels).
This has been long winded, but really it boils down to: Do you like wearing jeans, or do you have other casual clothing that works as well or better for you? Do you wear jeans a lot? Do you want to?
If so, a wardrobe of 10 or more would not be excessive for your life.
But if you don't want to wear them often, don't find them flattering or practical, or don't like them, there's no reason to wear them at all!
