Yes bitcoin is more scarce than gold. That's a true statement! But if you look at the acceptability of Gold and bitcoin, gold is a clear winner. Scarcity alone doesn't make something costlier. It has be adopted and accepted widely. That's how you can bet on its future value.
Bitcoin is a very new asset class compared to gold. It has a long way to go! So instead of drawing a comparison between these two assets, let's help in bitcoin adoption.
Apart from government backing of gold but not bitcoin, there are other things too. Since 1800, the innovation of technology has touched on in every area except the form of "currencies", but now it's evolved and has come with the name of crypto-currencies. It's a matter of time to get used to it.