Most technqiues of gaining Bitcoin are a waste of time, such as Bitcoin faucets or Bitcoin signature campaigns.
You need to do something at scale.
I would say trading is the easiest way to gain (which in itself is a form of gambling).
I agree with you trading altcoins is best way to earn bitcoins but i don't agree with you that trading is the easiest way to gain bitcoins because the most difficult earn bitcoins with trading is getting active profit, it needs time until find the best strategy of trading to getting constant profit even the trend of price is going down.