Honestly this is what I keep saying and everyone gets pissed when I do.
There's enough resources on this planet that every living human could live a decently luxurious life. But because we allow a small handful of us to hoard all those resources we have poverty on a global scale.
It's not so simple. They're cheaper than building non renewable, but are they cheaper than keeping the current plants running? Also, energy consumption keeps growing, and in many places, new generating plants using renewables usually only take care of the growth, and doesn't allow for room to take older plants out of operations. If we don't make huge efforts to reduce our energy consumption, I doubt we're going to get rid of non renewables so soon...