Here is my question;
would you feel secure to trade and invest larger amounts, big amounts ? on BTC-e
Or give me a raison why not to do it ?
I feel never secure when someone else has my money.
I have some coins at btc-e depot, but you never know if or when they shutdown down and run away with your coins. Or they simply got hacked and the hacker runs away with your coins.
You could trade high amounts of coins, but you should always withdraw to your wallet / bank account after the trade. Even if there are high fees for withdrawal fiat, but if you withdraw a high amount of fiat, the fee is not that much (e.g. 0,1% EUR for SEPA transfers higher than 10,000 EUR).