Well, see, you might both be late to the party and just coming in at the right time...
You might be late because by now, the asset stores are quite crowded with expierienced hobbyists and professionals who are delivering assets of incredible quality... can you compete with them?
You might come just at the right time as the Unity and UE4 community has also grown quite a lot in the last few years, and you might find more people willing to spend something on the asset store now than some years ago.
2 things to keep in mind:
1) Selling 3D Assets on a single game engines asset store will not make you rich. Most probably you will hardly sell anything, if you are not hitting some sought after niche (for example you were the only one selling a fully rigged zombie 3D model at the start of the Zombie-craze some years back).
You will need to branch out to as many different stores as possible to reach as wide an audience as possible. That includes engine asset stores, but could also include sites like turbosquid and similar 3D model stores.
Even then, be realistic with what you can make... there was a thread lately were someone was talking about what he makes with selling his 3D models in different online stores... I think he was talking about 150$ a month. I have no idea how many 3D models he has for sale, what his price point is or how many stores he sells them through, and of course 150$ could be plenty if you are just looking to stock up your budget for creating your own game. Some extremly awesome Thirdparty assets on the Unity store that I see as absolutely essential for high end Unity development are under 100$, so over the course of a year you could get everything you need with that kind of income.
2) Like any maturing market, selling stock 3D models is becoming a hypercompetitive market. I am amazed sometimes what quality you can get for quite a cheap price... So while I don't think there is any harm in trying, be realistic. Your first dozen models most probably are not worth much, as any buyer would have to fix a lot of stupid nooby mistakes you are likely to make with them. Make sure you price them right. There is always place for low quality, cheap models on the market... but given that you can get enough decent quality models for free, again, don't expect too much.
Last thing to add: look around in the stores. Find a niche, something nobody has made yet. Create models for that, see if you can sell it. Don't be number 1000 of 3D model makers who try to sell the same old plain zombie model in the same store and wonder why they seldom see anyone buying their model... be the only one that sells <insert your niche product here>, even if that thing is really a small niche, you might get better sales than with the done to death zombie model. And if you are lucky, your niche turns out to be the next big thing....
are you willing to take the risk
There is very little risk in making high-quality game-ready 3D models and textures. Adequate triangle count (100-4000 for most objects, may be less), optimized flat surfaces (no pointless subdivisions), well-shaped triangles (not too thin), stretch-less UV maps, power-of-two-sized and sharpened, well-packed textures (don't use 2+ where one is enough) etc. - such models are in a rather big demand. Bonus points for normal maps and specular maps, multiple levels of detail.
And, of course, presentation has to be solid. All models should be rendered with nice lighting both separately and in a scene. But that's extremely simple in both Unity and UE4.
P.S. I have no data from the profits of those stores. But I've bought some assets and seen other people buy assets as well - that is what they look for.
And, for additional profit, you might want to search the forums for what people would like to have but can't currently get. It's easier to profit from making things in sufficient demand (can't just listen to one customer, need to hear the needs of many) that have been overlooked by others.
Also, it's more likely to make a sale by selling sets of models and textures (included animations and rigging for character models), instead of individual assets. Stylistic coherency is appealing, and customers like to buy using the "shotgun method" (try many things at once so that it's more likely that something is immediately useful from the purchase)
Depends on how you do it... if its a hobby and you are creating the models anyway, no risk at all.
If you put everything on the line, give up your day job and try to live from selling your models online, you are taking a huge risk. Freelance work might be a safer bet then... at least you know you will be working on something for some months and have a secure income from that, instead of trying to guess what will sell how many copies...
Also don't forget that he calls himself a newcomer... I don't know exactly how new he is to 3D modelling, but a total newcomer will have a hard time producing anything of pro grade quality. Reaching that level of skill will take him some time. That doesn't mean he cannot try to sell his first few models... but it might turn out his models are not in such high demand, both because they might just not look so good, and also even if they do look good enough, they might not hold up from a technical point of view. If people buy his models but will have to fix lots of modelling mistakes afterwards themselves, they might choose someone elses models in the future.
Agreed though, demand is certainly there at the moment, and selling sets is a very good idea.
). I am pretty sure not all of these devs paid for the pro version of Unity, why would they if they make less than 100k$ a year selling assets (don't even know if selling assets is included in the 100k$) and do not need the pro only tools (though the profiler can certainly be useful)?
