You have a point, the OP owns his wife's startup jackpot in the eyes of the law. (Unless there's a prenup in the mix, which is not mentioned.)
But there's legal situations and then there is real life. If a discussion about money ever gets the lawyers involved, then the marriage is either way more high powered than anyone I've ever known or is in a pretty bad state.
To me, it’d be pretty weird to enter a lifelong agreement with someone to share everything, but then as soon as you hit the lotto you start to squirrel things away on the side.
Yes, as you also share terrible things like stress, anxiety etc that often comes with these kind of jobs. It might not feel as much but I know quite a few cases where the stay-at-home person burnt out severely because of the stress transferred from top manager or director or trader type of functions. Just all a bit weird; shared is shared to me.