You may be thinking about this wrongly. If you endeavor to be a millionaire and end up a happy hundred thousandaire, you may be moving goalposts. BUT if you can't be happy as a hundred thousandaire, you probably weren't going to be happy as a millionaire
Agree. That's why I said hundred thousandaire. Likely takes a Buddhist monk level of equanimity to deal with abject failure. But aim for the stars to land on the moon works for most of us.