I could also do an immitation of a dumb pedantic person and just answer your "First, zero dollars were spent adding null safety to languages? False", with: "I didn't say "zero" I said "Close to none". So PWNED! or something equally immature.

But one can also chose to be charitable. E.g. to understand that:

> Zero dollars were spent converting code to those languages? False.

Having null safety doesn't necessarily mean "converting". Could also mean not having nulls in a language to begin with. So "how many dollars does it cost to have null safety" in that case is zero. It's fixing the addition of nulls after the fact that can have a cost.

Even so, the conversion to null safety is not that costly (it's nothing like a rewrite, more like going around a program and fixing SQL Injection cases or XSS). It also makes evident many logical and safety errors in the initial program when done (many teams have written about such experience), and any cost has to be offset with the cost of those errors not happening anymore.

In any case, those are not costs of not having null to begin with in the language. They are costs of retrofixing code in ones that did have it.

> Zero dollars were spent solving problems uniquely created by not having the benefits of null? Also false.

There are no "problems uniquely created by not having the benefits of null". In fact, there are no "benefits of null" to begin with.

> Sounds like a crappy way to reason about facts.

Then again sounds like you didn't provide any facts. Just shown ignorance of computer science theory AND history, along with certainty and immature tone.