No one except the DDOSer, probably knows the reason behind the attack. It could be for fun (doubt it), trying to take down a competitor or it is someone who got mad that they lost funds. Could be an extortion attempt as well.
Yes. Since MoneyPot can't be accessed sometimes, the bankroll won't move during that time, and no profit/loss will happen.
It is happening because someone decided to attack moneypot. Read more here, if your not too busy spamming for YoBit. Maybe after you make your 20 posts?