In the final minutes of an interview with Fox News host Sean Hannity, Donald Trump claimed that he couldn't reveal whether or not he's running for president in 2024 because it's "illegal."
It's not true, far from it.
Trump's problem is that he wants to continue to raise money into his super PAC. Using that as his repository of cash, he can ask whoever he wants for money. If he declares that he's running for president, he can no longer do that and the super PAC staff must separate from the Trump office into its own entity. Trump would then only be allowed to fundraise into his presidential account.
It isn't illegal for him to say whether or not he's running in 2024; it's just inconvenient for the money he'd like to raise.
Another political problem for Trump is that if he decides not to run for president, his fundraising will disappear. People continue to support him because they believe he will regain his power, but if he drops out of the presidential race, the focus will turn to other Republicans who may run.