BTC and Gold has a lot in common, like the scarcity, both have limited supply, although gold's supply can be unlimited but that's depends on the new reservoirs, both are used to store for value, people have lot of money they want to store it in an asset where they don't lose the value due to inflation so both are best hedge against inflation, both are mined but with different method, although there are some small differences in them too like gold is hard to transport and carry while you can caryy and transport trillions of worth of gold's money in the form of BTC.
No it depends on the demand and supply and as you said it is decentralized, then why you asked this question.
For a long time it will be more profitable.
you can do the both if you have money and if you can bear to lose it, then I suggest you invest too, because without investing, you are like playing very safe and you won't feel those dynamics of emotions that are necassary for the real battle.