Can one make living through selling 3d models?

Honest opinion is your question should have been answered BEFORE you opened your store. Lately a lot of guys like you have been jumping in to the ocean and asking "how do i swim?" Not trying to be a jerk but it just seems people are getting the wrong idea. Selling models is not easy money. chances are that if your driving factor is a paycheck and you don't already have years of experience under your belt you will fail. If you are doing it because you are an artist and you want to be the best you can be and you feel you have something to contribute to the world, you may do ok. Ten thousand hours.

In short - Don't waste your time.

You will need to invest a lot of time to learn - modeling, texturing, lighting (this process never ends as things constantly change);
build a library of models, part of which actually make sells;
deal with constantly increasing competition and constantly decreasing prices of models;
copycats, undercutters, thieves...

Depends where you live in the world and if you do a lot of client work or not. If you live in a country where USD is a lot of money then you could just live off of royalties from 3d models on your store. If not, I would say that you would have to do client work alongside putting stuff on your store.

Hope I was helpful, Locki.

Of course. Just be a pro in your skills. Do not depend on just one platform. Make regular clients too. Online market places can not be guarantee to have regular income but definitely can help you earn enough money.