Tab is usually three spaces, right? So if I hit the tab key, I'm getting three button presses for the price of one. So extrapolating from that, if I hit tab I can get my work done three times faster and get out of the office quicker. If I'm using space, it takes me three times longer, which makes the boss think I'm working three times harder and I get a pay raise. I'm always at the office before she is (to fill in all the spaces) and I'm at the office after she leaves (still jamming that space bar). Sure the guy who uses tab ships code faster, but it must be worse code because he obviously rushed through it.

It looks good that I'm such a hard worker. So I get paid more.