I have read dozens of threads saying you need to keep your BTC on a hardware wallet or paper. Anything online isn't safe they say. When trading that is not really feasible is it? I like to move in and out of positions several times a day and often at a moments notice. My trading account has a sizable balance (to me - 5 figures) in it.
How risky is this and any additional things I could do?
The only group that is insured against hacking is Coinbase/GDAX. (Though Gemini might also be insured, I know they are fully licenced by New York State and I think the licence requires reserves to be held).