Altcoins have a volatile price, and stablecoin follow the price of the dollar or gold. You can see one difference, and I haven't found a project that can convert altcoin to stabilcoin.If there is, please provide a link maybe I was left out of information.
No altcoins that were meant to be assets have a stable price but there are stable coins that exist in the market like Tether which is also an altcoin.
Most of stablecoins are private owned and the coins that we consider as true coin usually decentralized and honestly it seems impossible to buy back all the coins that people already holding just to turn it into some stablecoin by adding some representation of reserve for each coin. Might aswell deploy a new coin since it's actually easy if done properly.
Yes, that's the basic reason why a decentralized coin cannot achieve the stability of a stable coin. There are coins that are relatively stable but we can't call them stable coin because volatility still exists.
Maybe a coin that hasn't distributed to many people yet still have a chance I guess.
Yes I agree, but you cannot control a decentralized coin even if it's new and not being traded much in the market.