Cassie does have a lot of money, thanks to some trans-temporal strategic gambling and investing. But as I stated on the FAQ, she enjoys her chosen career, so she stays on at her nanobot research job for as long as she wants it.
TRANSCRIPTION COURTESY OF JOSEPH HOUK - (BG, driving home with Cassie) "I feel so bad for Matt!" (CW) "Yeah, if it wasn't for him working next door to me, I'd have had a harder time putting my time machine together!" (BG) "Well, thanks to that time machine, you've gotten your finances to where you don't really need your job now... Can't you set up something for him?" (CW, as they arrive home) "I would, but if I know one thing about Matt, it's that he wouldn't want stuff made easier for him.. He likes working for a living, same as me. And besides, Allen sharing an apartment with him kind of complicates everything." (BG) "Yeah... That was kinda awkward at the restaurant tonight." (CW) "I hate to keep the time travel secret from Allen... But I don't think he'd react well to it." (BG) "Maybe so... But if he's the one you were meant to be with, you might as well find out if he's trustworthy." (CW) "You're right. Next time I see Allen, I'm gonna let him in on the time-traveling stuff!" (KS, inside the birdbath that wasn't there this morning) "Um... NOT a good idea." (CW, not even batting an eye) "And how would you know, Agent Scott?" (BG) "More importantly, how do you not feel cramped and twisted in there?"