Is there good money in making assets?
Yes, my store account has made about 200k in 4 years.Freelance work close to 500k in the same time. Steam sales for the last year close to 100k.However you don't simply start selling, you have to make a name for your self, quite often you will need to work for free or provide free work and build a rep and gain experience ect. Freelance deadlines are quite tight and often mean 13 -14 hour work days, the UK company I freelance with often, a 2 week project nets about $600 per project.
Once you set up a store account you need to keep uploading content as much as possible.Get rich quick schemes by uploading to already saturated turbo squid is a waste of time.There is money to be made with game ready assets, margins are decent, but you need lots of content.
My last steam project I worked on took close to 9 months to complete, it was released in December 2018, and I am still averaging 200-300 pounds a month in sales.The contract signed is for 5 years and provides me with a steady income, so I can do other projects and do projects I feel like doing.
I have also worked with other games engines producing assets for them on a freelance basis.
If you intend on getting rich quick forget it. It takes insane amount of work and the tools needed to be able to compete on a professional level is insane.
My workflow tools cost more then the average secondhand small car.
My workflow is as follows and because I am selling content I am often forced to buy commercial licenses for some tools, while free tools can work to some extend nothing beats commercial tools.
Pixplant
Softimage 2012
Toolbag
Photoshop
Quixel
Fragmotion
zbrush
Medusa ( Helps making rocks)
Forester ( helps making trees and plants)
Gimp ( Yes it is free but has some awesome plugins you can't find else where)
Then a large library of steam tools for sprite and 2d game asset tools, 4 or so different game engines.
Bunch of smaller free tools, that helps conversion of models and textures.
I did this for a hobby and spend a good 3-4 years providing free content, before I quit my day job to do this full time, about 5 years ago