Not to mention the video someone posted beloew from an engineer talking about Erlang there in 2014 has some interesting numbers. Christmas/New years is peak, and on Christmas Eve they were maxing out at 146GB/s out.

If we assume they maybe averages 75% of that over 6 hours, that's 146Gb/s * (60606)s / 8bytes/byte * 0.75 * 0.05dolars/GB = $14,782.50 for a 6 hour period (estimate).

That's highest listed bandwidth tier price for Azure, I'm sure they would pay less for a number of reasons. But let's just say that $10k for a whole day may not be out of the realm of possibility. That puts bandwidth costs possibly North of $3 million a year. Even at $1 million, that's a lot of money.

Ok but a serious company wouldn't pay per byte if they were trying to save money. They could buy that much connectivity for like 50k a month. (Though they'd need to get some switches and have a network engineer.)

And if that's audio/video Vs just text, clever NAT hole punching techniques could reduce it if truly needed.

But, it seems WhatsApp was on SoftLayer? In that case their costs might have been vastly higher.

Real costs per employee are 2-3x the salary anyways.

I find that hard to swallow for a small company size, such as being discussed here. Do you have a reference or some reasoning to support this? I'm interested to know where it comes from.

Benefits, office space, equipment, T&E, employment taxes, etc. This is an old article but it suggests about 2.7x. [1] I agree that it might be less for a startup assuming a frugal startup but it's probably at least 2x salary on average.

[1] http://web.mit.edu/e-club/hadzima/how-much-does-an-employee-... (This is old but nothing really substantial has changed except.)

I'm not sure a ratio-to-salary is the best tool here. I mean, why would a developer on $150,000 have twice the healthcare cost, or office space cost, or equipment cost of one on $75,000?

It’s just a rule of thumb and some costs do roughly scale. I’m sure there are more sophisticated calculators and spreadsheets for this sort of thing.

I'm assuming you don't run a business. 2-3x sounds in the right ballpark to me.

Why is everyone making 100,000?

That is a very conservative mean all-in cost per employee for a group of professionals. Edit to add: in the US that is.

Yes. That implies the average salary is almost certainly <$50K and maybe more like $35-40K.

Because they are developers?

Developers would cost way more than that, especially if you factor in taxes.