Private ship funding and merchant ships hired for war

What might happen if modern billionaires sponsored warships as wealthy patrons did in the past?

The older comparison largely concerns privately owned merchant ships hired for wartime naval use; no company-by-company prediction is offered.

Much of the historical comparison concerns merchant ships that owners hired out as warships during a conflict. Those ships could return to merchant service afterward. A more recent Greek benefactor is mentioned as a different case, without a name. No predictions are offered for individual modern companies because the required knowledge of their philosophies is lacking.