User blog comment:AYET/(99) The worth of the Shichibukai to WG/@comment-6920514-20130419214335

I think the Shichibukai are also supposed to give the WG a tenth of what they "earn" too which with Buggy becoming one just before taking his crew to find that treasure and with DD having all of his ventures I'm sure they funded the construction of some battleships all on their own or funded some of Vegapunk's research.