Variance of Coefficient of Probit estimation with 500 random draws

this is my first post here, I try to be as specific as possible. If a forgot anything important, please tell me :).

I have data with 100.000 observations about cellphone providers. The data can be seen as the whole population. First I estimate a Probit model with only one dependant variable and store the estimated coefficient and it`s variance to get the "true population values". After that, I draw 500 random samples of 50.000 observations from the data, estimate a Probit model for every sample and save every coefficient for the dependant variable in a vector. After that, I plot the density of the coefficient. All calculations until this point work and seem to be right (mean and distribution of the coefficient etc.). Now I want to estimate the variance of the coefficient of the random draws and compare it to the "true variance" which I estimated with the whole population. At this point I am struggling. My exact question is: with which formula or method do I have to calculate the variance? Since this question is more about which technique to use, I think providing code is not helpful. If it is necessary, please tell me and I will add it.

Thank you for every helpful comment in advance.