Because this early employee 1% is a) going to get diluted; b) it is over 4 years; c) most likely will result in $0 - $5000 cash-wise. And 50k (without benefits I assume) is.. well nothing.
Also, I'd love to take $50k/yr + 1% equity in an already successful startup. Say, Facebook.
It is never reasonable to trade your skills at substantially below-market compensation - regardless of if you can afford to do so. I have a lot of savings, but that doesn't make it reasonable for me to start lighting cigars with $20 bills.
Equity is a form of compensation, in this case dchichkov worked it out to be a expected value of $5K (or thereabouts) - how does one justify taking a haircut substantially more than this? (in this case, the haircut is on the order of $50-100K depending on the person).
Taking a significant paycut can be worth it if the options offered proportionately compensated the salary disparity IF the startup exits AND at a number that you estimate it could potentially hit.
If one isn't willing to take that risk then they should opt for less equity/no equity but a fairer market value.