Com'posers' without formal training, how do they do it?

We have many music composers in Telugu film industry without any formal training in classical music. Let alone classical music, i seriously doubt if they had any training in composing music. But they seem to do a good job of creating marketable music, how?

Singing is a different thing, practice makes you a good singer provided you have a good/passable voice to start with. Kishore Kumar is a sterling example of practice makes a singer perfect. But composing is a different ball game, isn't it?

I am not a composer, but something tells me that composing songs is not easy as copying tunes.

A few years ago RP Patnaik created a bunch of good songs, then got repetitive and soon faded into Kannada filmi oblivion. No formal training in music, but that didn't stop him from composing some classical numbers. Here's an example, check out "Chinuku tadiki" song from "Nee sneham". How did he do it?

Now we have Kalyani Mallik scoring music for Nagarjuna's latest movie Boss. He too doesn't have the benefit of formal training.
See my review of the songs below, except for a couple of songs (one of which sounds very much inspired) all others sound very amateurish. He is the brother of talented (but prone to occassional plagiarism) and famous Keeravaani. Thankfully for now, Boss's music doesn't make us suspect his lack of training. It is very much in line with it.

I am always sceptical of music composers without formal training. Sure, there are some who compose good songs sometimes, but in general they are not as good as their trained counterparts. I think a big reason for this is that owing to their limited exposure, they don't know where to copy from. Damn!