They are profiting out of mongodb, they are getting people to invest lots of time, trust, and money in their product.

The author has a strong point that quality of the development process for mongodb must not be good if a bug like this one gets into production, when it could be avoided using automated tools. This won't be such a fault for a random open source project, but if you are making a business out of it, and you are encouraging others to base use it as a key part of their business it do is a great problem.

Agreed. This is one of the unintended results of giving out free stuff in general; no good deed goes unpunished. There are enough bugs in commercial APIs and products that hitting one in something you got for free should be no surprise at all.

I always describe programming as incredibly easy, except for the part when things don't work as they're supposed to work. Very often you eventually find this is outside of your control. You have to be more calm and patient than the bug.

He's not going to win any friends or help acting like a pompous ass who's never made a mistake in his life. Maybe he hasn't because this is his first real project.