I believe trading of BTC is one of the best source of bitcoin nowadays . Bitcoin had reached more than $19,068,912,000+ cap which is an awesome . Increment of the bitcoin can also help a lot to trade bitcoin nowadays .
it proves that the velocity of money in the market of bitcoin is very large and this proves that bitcoin has a huge market and profitable. if you have a good knowledge in bitcoin. you can try trading
This also shows that people want to invest in bitcoin and the prices are a direct consequence of that. People are buying bitcoin and getting into trading bitcoin - this drives the economy. More and more traders are joining and the acceptance of bitcoin is growing.
The best source of bitcoin to to earn it by working for it. Side earnings can be from signature campaigns. Trading is also a good method to earn money, but you must have good knowledge of the market and have to keep tabs on the market price every now and then.