If I buy a lump of gold, and attempt to sell it to someone else later at a higher price, that is pure speculation. Gold is gold is gold. That lump of gold is going to be the same lump of gold a year from now or a hundred years from now. You might as well have buried the money in a backyard for all the change of affected in the world.
If I take that same money and invest it in a business -- the business is going to take that money and create something new. Hopefully what it creates will be worth more than what you invested, but in any case your investment has changed the world in some way.
I think a cryptocurrency is probably something in between that, because your 'investment' is actually ultimately going to miners who will expand the network, so you are actually building something new in a sense by investing in cryptocurrency. However I'm not sure that building the bitcoin network out is a net positive for the world.