Alright, I watched it again. While 10k was brought up, Pam agreed to put in up to $5k and even then, she knew the investment window was closed and Jim’s eventual offer was one of desperation and fear he’d be left out if he didn’t pay his way in w/ THEIR savings. Mind you, this is a job he arranged w/o her complete buy-in and the whole scenario makes Jim appear to have only considered his own desires and none of the family he’s part of. From her POV he’s arranging another job in another city and using a big chunk of their resources to do it w/o caring whether she’ll agree to any of it. (Similar to when he bought his parents’ house and decided where she’d live w/o asking if that’s what she wanted.)
Here’s your take on it when the episode aired last fall, for reference.