Whilst the theory is very sound, the reality is a fair way off. The recent contest to have a good enough tether didn't even get any qualifying contestants.
http://www.theregister.co.uk/2005/10/25/space_elevator/

This all boils down to combination theory from Monty Hall.As one other member has illuded to.
Though this video is obviously staged because of the random part of chance that could ruin it

Shows there are some very good reasons to do a Maths Degree, Gambling.