[LarryMade2]

>>- What are the reasons people decide to start a new OS development project?

They want to learn how to do it the hard way, they have ideas on how to do it better or just differently, why not?

>>- Why to maintain your own open source OS, and not to adapt or contribute to an existing OS?

They don't like how others are written, they are ignored or repeatedly flamed by some community they were interested in, they want to be in control, they don't like the change cycle or direction of the OS that interests them

>>- Who is behind these non-mainstream open-source OS? - What is the end goal of having your own open-source OS?

Aliens?, the Illuminati? Naw, jut geeks like us - for some folks low level OS development is a relaxing passtime.