I will choose campaign. No money will be required to campaign and there is no risk. I earn good money by bounty. On the other hand, trading and gambling both are risky and capital required.
I guess campaign also need money to start it, internet connection needed for it and yes, we must buy it with money. Personally, I also do like you, but after receive my rewards from campaign, I always hold it or exchange it into best assets, yes I'm crypto holder. 
I do agree, without investing we cannot able to get the internet connection, i think mining is not that much profitable we need to have enough hard requirement in order to mine the coins but you can see there are many people mining the coin which they have already invested money into it. Now the hardware equipment is very costly with the increase in demand for the miners.