1) That includes benefits
2) They are in Silicon Valley and have to compete with everyone else in Silicon Valley
3) Given what they have accomplished with such a small team, these are probably high caliber people.
4) In SV there is a good 25% premium you pay for engineers with security expertise.
As someone who runs a business and has to hire talent, I can say that I'd consider myself lucky to get such a team for such a great price.
Edit: A bunch of people are saying "why not remote". I think they are in fact mostly remote, but they still have to compete with SV wages because really good people command those wages whether they are here or not.
Edit2: As has been pointed out multiple times, the blog post was not clear, and it is actually 200K per person, all in.