To put the number in perspective -- this is about how much a single full time engineer will cost to employ. Let's lowball and imagine that OpenBSD in comparison to firefox is 1/100th the size. Mozilla has annual revenues of >300 million dollars, compared to OpenBSD's $150 thousand.
They are asking for donations to cover electricity costs. The real donations, of course, has been in the time the community has put in this.
I hesitated posting this because I do not want to give the impression that OpenBSD is not worthy of donations. That being said I am not sure that it is useful to present Mozilla's entire annual revenue as it is all for Firefox. Mozilla does a lot more than just Firefox.
Workforce and expenses are closely tied together, and those depend on how much you have to spend. You can't spend 20 million dollars or hire 100 engineers if you don't have the budget for it.
They are asking for donations to cover electricity costs. The real donations, of course, has been in the time the community has put in this.