I think aside from earning bitcoin through android app there is still good way to make huge amount of bitcoin.
I agree with you that you can still earn bitcoin through android app but for me it still good to earn bitcoin through joing signature campaign. Some people earn bitcoin through investing and trading.
I also join some signature campaign which help me to earn bitcoin especially if you in weekly campaign where you need reach the requirement posts and they will pay you in bitcoin. In addition to that, right now I doing
investment which can totally help me to earn huge amount of bitcoin and as a matter of fact doing investment is one of the source of bitcoin. Nowadays many people conduct investment simply because it is profitable and your capital will assure become double.