Yea where I live I get 7% (over inflation) on treasury bonds (it's kinda insane here, but 5.5% does seem like a low value). I assume all missions are fully insured to prevent bankruptcy with such low margins?

If it is so I would imagine simply improving the reliability track of the vehicle to lower insurance would have a very large effect on profitability. If they could eventually tank the insurance partially/completely in house (given a low chance of failure) that would be even better.