A developer doesn't manage anything beyond their own organization. They make deals, arrange financing, design, and construction, and then move on. Once the developer is done, the responsibility for managing the project goes to the owner and their facilities manager. So, Trump. Who has never managed the on-going business of even one major building and is most likely deeply uninterested in the day-to-day operations of facilities management, which quite literally includes taking out the garbage, as well as other pleasant tasks like cleaning the floors and changing light bulbs.
Many of Trump's deals go sour; the properties go bankrupt and the owners and investors are left to take a loss. But Trump has moved on before they fail.
The work of the executive is mostly on-going management; implementing legislation that is developed in Congress. The Chief Executive also has a role as "head of state"--the visible symbol of the USA. Trump wants to be head of state, but he also has the job of chief executive. So I suppose he will shirk the job, leaving the Koch mouthpiece Mike Pence and his merry men to do the work, which they are not qualified for, and the Republican-led Congress to develop policy, which they also are not qualified for.
Is the Republic to end because of incompetence?