Paying millions of dollars for a few talented engineers, who will probably work half-heartedly for a few months/year, depending on the clauses in the contract, then move on to the next startup? Come on, USD is not that weak.

Their value is not just in being there. What they create will likely exceed the acquisition costs.

I can see this, but it's not one of those things I'm so certain of that I could defend that point of view in a discussion with someone else. It'd be interesting to explore the reasoning behind it more.

> who will probably work half-heartedly for a few months/year,

That's what 4-year vesting is for. Besides, part-time work from an expert is better than full-time work from the hoi polloi.