Quoting from Sotomayer’s dissent (pp 29-30, paragraphing my own):

This new official-acts immunity now “lies about like a loaded weapon” for any President that wishes to place his own interests, his own political survival, or his own financial gain, above the interests of the Nation. Kore- matsu v. United States, 323 U. S. 214, 246 (1944) (Jackson, J., dissenting).

The President of the United States is the most powerful person in the country, and possibly the world.

When he uses his official powers in any way, under the majority’s reasoning, he now will be insulated from criminal prosecution.

Orders the Navy’s Seal Team 6 to as- sassinate a political rival? Immune.

Organizes a military coup to hold onto power? Immune.

Takes a bribe in ex- change for a pardon?

Immune. Immune, immune, immune.

They go on with an incisive critique of the majority’s reasoning:

Let the President violate the law, let him exploit the trap- pings of his office for personal gain, let him use his official power for evil ends. Because if he knew that he may one day face liability for breaking the law, he might not be as bold and fearless as we would like him to be. That is the majority’s message today.