My "minor problem " with ETH

I would like to say firstly that I think ETH is a great project and I'm not criticizing. I just want an explanation. Ethereum and bitcoin both are big project with bitcoin considered as digital gold. A lot of analysts say that ETH will be bigger than BTC. I want explanation in terms of price stability and how "decentralized " is it. I think that eth not have a fixed supply makes the price centralized because at any moment they can add more supply and the price will go down hence they can "control" the price. If I'm wrong please explain to me and explain how will the price rise up. Thank you