I have no evidence that the opportunity you claim is better is actually better. Especially in the ways that matter most to me, many of which can’t be determined until you’ve been at a new job a few weeks. And then there are the obligations I feel to my teammates (if not to the company), which I don’t take lightly.
And hopping jobs all the time doesn’t look great on a resume. If I’ve been somewhere 11 months and don’t hate it, taking that slightly better opportunity is probably a poor choice.
Dream job might be another thing, but I highly doubt your open position is anyone’s dream job. Nothing personal. Just that the odds for any given startup are extremely slim.
Now, offer a private office or a 10 minute commute on foot or 10 weeks PTO annually or to increase my salary by 50%, and I’ll at least hear you out.