Statistics of drawing a single hourglass in a 7 card draw for a 50 card deck: 60% with 5 glasses, 51% with 4 glasses.
I would consider going 6 hourglasses too, for a 67% chance.
But statistics don't force you do do anything its the fear of losing that makes you use your "statistics" to make that fear go away, using personal experence you already know how you play, how muck luck you have and what YOU need to win.
Of course statistics don't force you to do anything. They point you in the right direction and help you make the right decisions about a deck, since deck building and this game really is just math.
Otherwise, that's just stupid.
Let's say Harvard accepts 10% of applicants. So you *should* know that you need to work really hard to get in. However, your sister got accepted, so based on your personal experience, 100% of the applicants you know got in.
So based on your personal experience, you know that you'll get in to Harvard.
So you apply without really trying that hard and get rejected. You should have looked at the statistics and seen that only 10% get accepted. Your personal experience with your sister getting in means nothing.