He gives a comparison estimate that each Saturn V cost about 10^8 each. Per quick Google search actual cost in 1970s dollars was $185m which is $1.15b today: https://en.wikipedia.org/wiki/Saturn_V#Cost (important, but unrelated to rest of computation fact is that this cost was amortized over 35 flights)

10^11 is 1000 * 10^8, applying same inflation to 10^11 we get $1.15t. To put this number in a context, Iraq war is estimated to have long term cost of $1.1tn to $1.92tn: https://en.wikipedia.org/wiki/Financial_cost_of_the_Iraq_War