That makes two of us. Once I set my trading capital, I am more concerned about how much money I will withdraw on a monthly basis. This is trading, not like an investment where the money just sit there with guarantee of interest annually.
Roughly 95% of my liquid net worth is in my trading account (which funds both my long term positions and short term trading). I can never understand why any trader who has no near term financial commitment would want to put his money elsewhere... unless he doesn't trust himself to properly control risks? Maybe these people are just gambling, in which case it matters not what you have in your trading account because you will have to fund it again after the inevitable blow up.
The only investments that guarantee you interest annually with zero loss of capital are CDs and treasuries (if you hold them till maturity anyway), a skilled trader should have zero issue beating the risk free rate, unless he doesn't really have any skill to begin with.
If he doesn't have any trading skills, then a PAMM account would be better used. There you will find expert investors to follow and automatically copy their trades.