Pirate King: With Billions, Sweep the Seven Seas

Isekai'd to 18th-century Caribbean as a broke pirate captain. A system gives 1 gold daily per loyal crew. He must reach 10,000 in a year or lose his license—and repay a mermaid 10,000 gold or become her fourth sunken groom.

With a sea siren and dwarf shipwrights, he crushes a voodoo fleet and hits 10,000. His pirate king journey begins.