Jet, with all due respect. Yes, you did not get it this game. It is very, VERY EASY and CHEAP to protect your colony from 400 Battleships. When I did a math I said to myself at the beginning of the game - there is no point to build 400 battleships since it will be useless against reasonably defended colony. I build my army only to fight aliens. Then later on I noticed that almost all players put a sign on his/her home worlds: "Please conquer me. I am totally undefended. I do not know what I am doing".
I repeat as a winner on Aruru of 18 home worlds: It is almost impossible to take down reasonably protected home world! My own home world could not be taken by 1000+ battleships. The attacker is in serious disadvantage against properly protected colony.
I think a simple knowledge about this fact will render idea of attacking home worlds obsolete in the future games.