Actually, there are many ways to earn btc but somehow in my own opinion it could be bounty campaign where you don't need to cash out and all you need to do is your participation once you are already a jr.member upwards, you are entitled to join and earn. However, this will take sometime to be able to earn wherein the shortest time possible could be within two months and up to 8 months could be the longest. If you had a sufficient capital, I believe investing in btc could be also consider as one of the easiest way because this is the only crypto for now that could rise high than the altcoins.