Will people still use or buy bitcoin till today if all it has to offer is the decentralized characteristic only, I am trying to say that if bitcoin is stable in value from day one and has no investment ability will you still buy it?
What do you mean by "stable in value"?
That it can buy the same quantity of eggs? (In what country?) The same amount of real estate? (What location?) The same number of iPhones? (The same model or the model computed by some kind of hedonic adjustment function?)
Or, God forbid, the same amount of US dollars, Argentine pesos or some other f**t poocoin?
Whichever you choose, it's impossible to peg its price to that of another asset while keeping it decentralized at the same time, because you'd need a redeeming counterparty. You could approximate a peg by setting the block subsidy to debase it as much as economic growth taken from some consensus-driven, decentralized oracle, e.g. if the economy grew by 5%, let's agree to print 5% more. Or the same for eggs, if you want to peg it to eggs. E.g. if the supply of eggs grew by 5% and the demand for eggs grew by 7%, then eggs are roughly worth 2% more, so you need to make Bitcoin worth 2% more by burning some.
But that doesn't take into account the increasing adoption. After all, we started at 0% and are heading towards 100%, and that alone is causing appreciation.