Well, there are not many slingers in the world, many if them make their own slings.
So right from the start it's a very small market and already very well served.
Noocs probably gone about it in the most businesslike manner.
He makes pretty decent slings, set up his own website (pretty simple, and really cheap as long as you don't go down the popular platforms)
I believe he also made cutting dies, for hud sling pouches.
If I'm making a batch if leather pouched, I'll use my laser cutter, for cutting and engraving the pouches and finger loops.
All this kind of thing cuts down on time and effort involved.
At the end of the day Sarosh, you've just got a leather pouched para cord sling.
I think you said it took you 4 years to develop.
I've got nearly 40 years sling making and experimentation experience, and every now and then I'll still change something minor.
4 years is just starting out
So yeah, making and selling slings is always going to be a 'hobby'.
There's just too many people doing it, and no actual 'need' for any more.
Being self employed might look like a good idea, but I wouldn't recommend it.
If you can get a proper job, then get a 'proper' job