"I don't think necessity is the mother of invention -- invention, in my opinion, arises directly from idleness, possibly also from laziness. To save oneself trouble."
Simple: I don't think it's need that makes people think of new things. I think people think of new ways of doing things only because they are lazy and don't want to work hard. To save themselves from having to do work.
What it means: New ideas come from being lazy when it comes to doing something and wanting to do it in an easier way because of it.