Why do people use enums in C++ as constants while they can use const?

I like the automatic behavior that can be used with enums, for example:

enum {NONE, START, HEY, HO, LAST};

Then it is easy to loop until LAST, and when a new state (or whatever is represented) is added, the logic adapts.

for (int i = NONE; i < LAST; i++)
{
    // Do stuff...
}

Add something...

enum {NONE, START, HEY, WEE, HO, LAST};

The loop adapts...

Using an enum documents the valid choices in a terse manner and allows the compiler to enforce them.

If they are using enum store global constants, like Pi, for example, then I don't know what their goal is.