I do not know what makes this bitcoin special compared to other currencies and commodities, whatever makes people interested in investing here, obviously this bitcoin is very special what makes it special that's what makes special bitcoin.
You still don't get why bitcoin is so special compared to others? It's simply because it has high value, we are not here if bitcoin doesn't have a value or has high value. But being treated as an investment now is what makes bitcoin so much special than others. You just buy and hold and wait for it's value to increase and you have the profit, this is what everyone likes when it comes to earning.