Get a job and buy Bitcoins. Simple as that.
That is very simple yet it does not answer the question, the truth is there is no way to earn free bitcoin, even the method you describe it is not free since you need to wok hard to earn fiat and then use that money to buy bitcoin.
yeah its really a good advise to buy bitcoin with your fiat money and then hold it as the long term investment and bitcoin price rise to higher value then sell it with high price and make some profit.