Like a lot of people have said, it's astute saving and budgeting. I only have one Birkin at the moment and a few bracelets/scarves/Twillys, and now I'm saving up for a Kelly. I don't eat out, I rarely go out or drink alcohol, I don't drink coffee or live anywhere near a Starbucks, I don't have a driver's license so I don't have to worry about a car for the moment, and I walk to school, and I have no children or boyfriend to suck up my disposable income. 
I am still in college at the moment so my parents fund pretty much my whole life, but they are extremely generous so long as I'm still in full-time education and work hard there. Most of the money they give me goes on H, other bags, travel and jewellery. Sometimes clothes because in the last few years I dropped from a size 9/10 to a size 5/6, so I had to replace pretty much my whole wardrobe, but it's once again overflowing so I guess I can stop buying now! I think really that unless you are exceptionally wealthy, it is a matter of keeping an eye on where your money is going and having a large proportion of your income be "discretionary" due to not having rent/mortgage/car payments/kid costs, etc.

I am still in college at the moment so my parents fund pretty much my whole life, but they are extremely generous so long as I'm still in full-time education and work hard there. Most of the money they give me goes on H, other bags, travel and jewellery. Sometimes clothes because in the last few years I dropped from a size 9/10 to a size 5/6, so I had to replace pretty much my whole wardrobe, but it's once again overflowing so I guess I can stop buying now! I think really that unless you are exceptionally wealthy, it is a matter of keeping an eye on where your money is going and having a large proportion of your income be "discretionary" due to not having rent/mortgage/car payments/kid costs, etc.