When running a business, you need to budget 3x salary for actual TCO of a staff member:
1x covers their direct salary 2x covers retirement fund, electricity, office space, and infrastructure items unlike server and laptops for corporate use etc.
The 3x multiplier is for when you're a services company, and that represents a possibly profit margin.
So for signal, your $380k becomes $190k which in my experience is average for a US tech sw dev at a mid to early senior level.
I donate to signal monthly and I have no problems with the costs they're posting. I work in SV tech and I've seen 20x worse numbers.