Modelling economic value of risk-reduction DevOPs efforts
You are probably unable to find data on this for two main reasons. Firstly, because it varies from system to system. Does an outage cost you money due to contractual obligations? Or only in lost reputation and in user perception? How much does that cost? This varies from organization to organization. But I think that might be what you are getting at with the Bernoulli variable...

...Which brings me to the second thing. In order for you to be able to model risk, you need research in which someone has already statistically proved or measured the efficacy of DevOps methodologies (which means you have to define exactly what DevOps is first, a notoriously tricky issue.)

You also need to be able to compare that to old methods - meaning that someone must also have measured data for the Dev/Ops segmented model. I'm not sure that research exists or is settled. Probably because the efficacy and cost of Dev/Ops will also vary widely from organization to organization. In that respect it may provide an opportunity to measure the old methodology and then show the average improvement of changing methodologies if you can find enough research subjects.

In short, it is doubtful that such a formula for risk modeling exists. If it does, it likely exists as paid marketing research to a consulting firm and is unlikely to be available to the public and I would personally be very dubious of the accuracy of it's results due to the subjectivity of the input variables measured.