On this marketplace is very hard to sell models

Others would disagree with you...

CGTrader has around 630,000 models on the market place and you only have 15 models on your profile. You should make more models and upload them.

Looking at your Audi R8 model, there is only 3 renders of the car. You should upload more renders including wire frames to show your topology. Cant tell if you have added textures with the product but it doesn't appear you have from the available formats list, that will help as customers want textures to go along with the model. The description of the is only a single line and doesn't give the customer any information about the model.

Fixing those type of things across all of your models might help. But you have to ask yourself whether you are selling, advertising and marketing your models to the best of your ability because if you're not, you are going to struggle making sales.

Your models are in very crowded category with lots of similar things for very low prices.
Try get creative and diversify, use the newly installed analytics system to get a notion in what category there still is potential to make a difference.

Also in description you have a chance to connect to your potential customer, doe you just want to tel him “all my project is made by my own”? How would that convince him that is what he needs?
There needs to be real information, try visit successful profiles to get inspiration, look at what those sellers wright down in the description area, ask yourself questions why this or that would be useful to tell.

Try convince your customer with detail info, gain his trust.

Also more presentation renders definitely, with current profile you would probably end somewhere on page 50 where almost no individual arrives.

Try maybe use external means (social profiles, other art website, etc) to get some more traffic/views and get better position and then even more views and hopefully first sales that will instantly trow your goods some pages up.

But then again, main problem will probably persist (crowded category with lots of similar things for very low prices) diversify to salve that.

That's weird, I have sales every month, although not a lot, it adds to my other sales. Good marketplace in my opinion.

The highest amount I ever sold in one month on Turbosquid was 19 models, the highest amount I ever sold in one month here was 46 models + way better royalty and bigger payout.

My reality is that this place is actually the easiest to get good sales, no place anywhere on the net will probably do better for me.

Recently have put all my models offline on Ts, latest policy changes has made that platform completely irrelevant for me, I’m waiting to see platform rules change for the better but it doesn't look well, probably can wait forever.