Evaluating offer that is a promo but low-ball stock

Currently a 5a at Uber, got a staff engineer offer at a fast-growing startup called Sonder (staff for them being like Uber's L5b or high L5/low L6 in general) in the bay area that recently became a unicorn. They claim to be a rocketship, constantly compare themselves to Uber, Airbnb, etc. Salary: 205k Bonus: none Stock Options: $220k worth (at preferred price) over 4 years. I feel like this is crazy lowball stock options, but they insist it's a great offer because it'll come out to market rate when they 5x in valuation in the next 2 years. They have been growing rapidly and just raised a series at a 1B+ valuation, and I can see them potentially growing 5-15x in the next 5 years as they think they will, but this seems optimistic. They'll need to continue beating out other well funded competitors in the hospitality space (essentially leasing buildings as hotels). That all said, it just seems crazy to me to expect 5x growth just to get to market rate comp. Data on stock options offers are pretty limited on Blind, so looking for advice and perspective. Expected 2020 Uber TC: 315k (salary 175k) YoE: 4 + PhD Location: SF