Directly or indirectly the people of the United States have power over all three branches. One can easily make strong arguments that the problem here is both that Congress as abdicated its powers to the executive (rather than delegated), and that the people have ignored that Congress should retain those powers while focusing on the presidency as the important election to the exclusion of all others.
This has been going on for decades or longer.
>So if it decides to spend $X on something specific, it has to be spent on whatever that something is. The President doesn't have discretion in that case.
Sure. Definitely means he can't spend it on something else. But how much wiggle room is in this? Does it say on which day, hour, and minute it must be spent? Sure, it's probably tied at least to the fiscal year (in which case it needs to be spent by September, one would suppose), but that's months away. Does allocating a budget imply that it needs to be spent at all? If some bureau or department fails to spend all of its budget, has the president somehow committed some treason-adjacent crime, or is that just thriftiness? Are these funds earmarked for specific universities? What if he just goes shopping for alternative recipients?
To say that he has no discretion at all is absurd, if that were the case then Congress would have mandated that these be automatic electronic bank transfers without any human intervention (or oversight). The nature of the job not only implies but practically demands some (if limited) discretion.
