Many games feature money, but most of these lack any way to invest or spend meaningfully. Talisman, for instance, let’s you „invest“ gold pieces, but not in the way you probably have in mind.
I rather think any game with a market mechanism, where you invest for future gain, could fit the bill.
Acquire would be a good example (and a very good game), just like many modern Euro games. I have no idea whether Acquire is suited for 7 year olds in general, or this one in particular, however.
Monopoly - to adress the moribund elephant in the room - seems to fit the bill, but it‘s dated, and you can get way better games today.