[newb question alert] and how do you get full time on btc? by trading, looking for profitable investments and mining, etc? can that fill your entire time? 
Trading and looking for investments would really take quite a bit of time to be honest. Mining literally all the time spent is just the machines so unless you need to set up or fix something it is auto pilot for coins.You are right it really takes time if you have a profitable investment. Trading might takes a time but patience is always a virtue in trading.
I guess putting up faucet sites, and managing other profitable sites that earns bitcoin are the work for bitcoin full time.