my friend just told if I level up a account have melee combat level like 80/80/0 will more expensive than a account 80/80/80, can someone tell me why??

it will not be more expensive it is just his choice because he is probably staking on that account and staker dont usually have defence hope that helped

Because people are more interested in buying pures than mains. Your friend neglected to tel lyou that if you make a pure and want to get alot of money for it you will need to do quests on it also.

It will be more expensive because people can use it as staker and a pker. Also if they get borred from 1 defence they can always train it up theirselves. If the account had 80 defence to start with, pure pking / staking wouldnt be an option any more.

0 as in 0 defence?