Yes,holding of bitcoin is safe but I don't agree when yu said holding of bitcoin is not profitable cos holding is profitable. Are you saying some people that bought bitcoin when the incident of bitfinex happen don't make any profit now that the price of bitcoin is $625?
Correct. As for me, I see the event of an exchange being hacked (and Bitcoin's price decrease) an opportunity to buy more cheap Bitcoin. Usually, when this happens the price of Bitcoin recovers after a few days and then you can make a very nice profit. Also, holding your Bitcoins right now will turn out to become very profitable in the end once the price starts climbing towards the $1000 mark. It is best to keep your coins safe in a paper wallet or a hardware wallet such as Trezor for use as a virtual vault.
It is profitable but it is a long term investment and not like a daily income. Trading can be a good source of daily income if you are good at it but it is not a steady income too because you can do bad trades and there will be no income.
Yeah if you make perfect moves in trading then you can make some profits on daily basis but its also a risky as you cannot expect to make profits every time.