Program exits upon calling await

I have a while-loop that should repeat the program until a certain condition is met. Inside this loop I call an async function, which prints out a message for me. Here is the (cut-short) code:

private void InitializeMessageSystem ( ) 
{
    do
    {
        // Do stuff
        await printMessage ("Hello World!");
        Console.ReadKey();
    } while (condition != true)
}

And here the function PrintMessage():

private static async Task PrintMessage (string message, int spd = 1)
{
    int delay = 50 / spd;

    string[] words = message.Split(' ');

    int index = 1;

    for (int word = 0; word < words.Length; word++)
    {
        char[] current = words[word].ToCharArray();
        if (index + current.Length > Console.WindowWidth)
        {
            Console.WriteLine();
            index = 1;
        }
        for (int c = 0; c < current.Length; c++)
        {
            Console.Write(current[c]);
            await Task.Delay(delay);
        }
        Console.Write(" ");
    }
}

Edit: Here's the call from the main function:

static void Main (string[] args) 
{
    InitializeMessageSystem();
    Console.ReadKey();
}

Question

Why does my program exit, when I press a key while the function is not yet completed? I thought the program would wait for the Console.ReadKey() until the function PrintMessage() is completed?