My chances are 50:50

Embroidery thread comes in adorable little hanks like this:

Note the 2 loose thread ends.  That's where you pull out the thread as you use it.

One end, when pulled, dispenses lovely lengths of thread ready to be used.  The other end, when pulled, results in a huge tangle.  Obviously, my chances of getting it right should be 50:50.  Then why am I getting this with far greater frequency than 50:50?

It feels as if I'm caught in a version of Rosencrantz and Guildenstern where, instead of all heads, I'm getting all tails.  Tangled tails at that!