Trump lost money by becoming president. Perhaps the only person to do so in the past 100 years.
First of all, lets get one thing straight... Trump is a failure as a businessman. Multiple bankrupt casinos, a string of failed businesses and scams (Trump university, Trump airlines, Trump mortgage, etc.) Basically he is always losing money, and some of the money he does have he obtained under questionable circumstances.
About the only legitimate source of income he had for years was from his appearances on The Apprentice, which he used to prop up his other businesses.
So, Trump was "always" losing money.
Secondly, as other people have pointed out, while Trump "claims" he lost money as president, the reality is quite a bit different. Lets take a look at some of the ways he has benefitted financially, shall we?
- He had a hotel in Washington, that other countries would book rooms in as a way to curry favor with Trump (See:
https://www.cnbc.com/2018/12/06/saudi-lobbyists-reportedly-booked-500-rooms-at-trumps-dc-hotel.html)
- U.S. military flights were stopping near one of Trump's resorts in Scotland and booking rooms. (See:
https://www.politico.com/story/2019/09/06/air-force-trump-scottish-retreat-1484337)
- The secret service pays for rooms/services at trump properties while protecting him. In some cases, the fees were far above the going rate. (See:
https://www.theguardian.com/us-news/2024/oct/18/trump-overcharge-secret-service-hotel)
- The publicity from being president has allowed him to sell things like Trump electronic trading cards and crypto currency
So yeah, instead of the presidency "costing" him money, he is benefitting from it financially.