Meh... In
most cases, talking about "passion" in this context is just a roundabout way of saying "we want people to work harder for less compensation." Expecting founders to have "passion" is fine, since they (presumably) own equity stakes that will make them wealthy if the company is successful. But unless you're giving your early hires a large stake in the company, I'd suggest dropping the "passion" verbiage and treat them like mercenaries - like every other employee. Your vision, your dream, your passion, etc. are
yours... there's very little reason to expect other people to share that, given that they likely
already have things that they are passionate about, visions they care about, etc.
Hire the guy (or gal), scale their compensation to match the amount of work they actually do and call it good. If you're worried about them leaving too soon if their side project takes off, you can always try some "golden handcuffs" in the form of some perk that disappears if they leave before X months. And who knows, maybe that would make them decline the offer. In which case, honestly, everybody probably wins in the end.
Hire the guy (or gal), scale their compensation to match the amount of work they actually do and call it good. If you're worried about them leaving too soon if their side project takes off, you can always try some "golden handcuffs" in the form of some perk that disappears if they leave before X months. And who knows, maybe that would make them decline the offer. In which case, honestly, everybody probably wins in the end.