Ways to earn btc:
1- Faucet (you earn little and in a long time, but the little you earn can go up in value).
2- Participate in altcoins airdrops. (most shit but some is gold)
3-Trading altcoins, you need investment and training
4- profitable mining needs cheap electricity and heavy investments.

if bitcoins are digital currency why do the bitcoin creators dont just create or modify bitcoin amounts?

From: Satoshi Nakamoto <satoshin@gmx.com>
Date: Sun, Apr 12, 2009 at 10:44 PM
To: Mike Hearn <mike@plan99.net>

-snip-
My choice for the number of coins and distribution schedule was an educated guess.  It was a difficult choice, because once the network is going it's locked in and we're stuck with it.  I wanted to pick something that would make prices similar to existing currencies, but without knowing the future, that's very hard.  I ended up picking something in the middle.  If Bitcoin remains a small niche, it'll be worth less per unit than existing currencies.  If you imagine it being used for some fraction of world commerce, then there's only going to be 21 million coins for the whole world, so it would be worth much more per unit.  Values are 64-bit integers with 8 decimal places, so 1 coin is represented internally as 100000000.  There's plenty of granularity if typical prices become small.  For example, if 0.001 is worth 1 Euro, then it might be easier to change where the decimal point is displayed, so if you had 1 Bitcoin it's now displayed as 1000, and 0.001 is displayed as 1.