In any case, even accepting an argument as retarded as that

There's no need for language like that. Anyway, for countries where resource wealth (e.g. Russian oil and gas) is a big chunk of the economy, population can indeed have a big effect on per capita wealth (see Kuwait, Saudi Arabia). Likewise, if you have big wealth inequality, e.g. between peasant farmers and urbanites/factory workers, famines among poor farmers can easily raise per capita income.