Wilbur L. Ross, the billionaire investor expected to be nominated as the next commerce secretary, has made his fortune through the tricky business of buying deeply troubled companies. With wealth estimated at $2.9 billion, Mr. Ross, who turns 79 on Monday, would join a cabinet that is already expected to include one of the superwealthy in Betsy DeVos, the nominee for secretary of education, and that may soon have others. In choosing Mr. Ross to be the face of American business for the rest of the world, President-elect Donald J. Trump is turning not to a cautious corporate chieftain, but to a risk-taking speculator. The stark contrasts reflect the nature of the world in which Mr. Ross operates: distressed investing. He made his name scouring the landscape for businesses left for dead that he could sink money into and then profit from when they were resurrected. Like his investing, the politics of Mr. Ross, a former Democrat, do not always stick to orthodox points of view. Mr. Ross has expressed strong conservative beliefs on some issues favoring big tax cuts for businesses, for example, and a repeal of President Obamas health law. Yet Mr. Ross has also suggested that he is receptive to some of the anti-trade views favored by American labor unions and by Mr. Trump. The president has a huge amount of fire in terms of abrogating treaties, and he can do a lot without reference to Congress, Mr. Ross said in an interview the day after the election. Mr. Ross, a member of Mr. Trumps economic team during the campaign, said he expected the new president to do a lot on trade and regulation through executive action.