I think you forgot about this part of the article you posted:
"WASHINGTON, Nov 15 (Reuters) - U.S. President
Donald Trump bought at least $82 million in corporate and municipal bonds from late August to early October
including new investments in sectors benefiting from his policies, financial disclosures made public on Saturday showed."
He clearly expects to make far more money than he has invested, thanks to his own policies, apparently instituted for that very reason. It incentivizes those sectors to support him as well--he's effectively buying their/bribing them for their support