There is an alternative. Vest and buy the shares as soon as possible. This way, your taxes stay low, and you don't actually pay that much for the shares.
You aren't risking hundreds of thousands of dollars, only maybe 10s of thousands.
Not really if you join a unicorn, as this article was about. Unless if your grant is relatively very small, in which case you're not getting much benefit to joining the unicorn in the first place, at least in terms of possible stock upside. If you join a unicorn and your grant is anything less than $100k then you're getting a raw deal. (Again, at least in terms of stock upside, there may be other reasons to join.)
You aren't risking hundreds of thousands of dollars, only maybe 10s of thousands.