There aren't many good startup engineers with experience at successful startups who are floating around, especially from when the company in question was actually a startup.
edit: i re-read, my comment "failed startup engineer" may have read differently to what i intended. I meant they worked at a failed startup, not that they were a failure. It's largely unfair, but people do seem to think people who worked at a successful company are better than those who worked at a failed company.
From my experience, the choice isn't clear favoring BigTech engineers either.
For example, a pattern I noticed among the pool of BigTech engineers recruiters would pitch to me was the following. The engineer would join a startup with an immediate promotion in title, and then 18 months after the fact, they would jump back to BigTech to a higher level than the one they had when they left. When you asked what they delivered at the startup, it was clear that they didn't do much or often couldn't correlate the impact of their features to the ROI of the business. Nevertheless, the title upgrade in their resume helped them game the recruiter search and the BigTech ladder.
https://www.teamblind.com/ is full of recommendation for similar strategies that BigTech engineers use to climb the ladder.
Also, the good startup engineers aren't floating around, but you can still poach them. You'll have to give them a big signing bonus to cover the purchase of their options, but it isn't a risk to me when they are sure bets; a recommendation from my network for example.
There aren't many good startup engineers with experience at successful startups who are floating around, especially from when the company in question was actually a startup.
edit: i re-read, my comment "failed startup engineer" may have read differently to what i intended. I meant they worked at a failed startup, not that they were a failure. It's largely unfair, but people do seem to think people who worked at a successful company are better than those who worked at a failed company.