There are always naysayers or people who simply do not believe your idea can potentially work.

I was there recently, some guys told me you can't make filament at home cheaper than what you can get from Amazon.

And then I made my own filament: https://medium.com/endless-filament/make-your-filament-at-ho...

Now I am selling my filament on e-commerce websites under my own brand name and making good money, I'll clear $4000+ in sales this month alone.