She is ridiculously rich regardless of whether she holds other business concerns. So I don't think you could ever say Saints is her main concern from a pure fiscal standpoint. But on the other hand, I do believe that she is personally invested in the club and wants to see it succeed long-term as an entity.
To me, she has just the right amount of skin in the game. It's not just a toy for here where she can spend as much as she wants and if she gets bored can sell. OTOH, she has enough personal cash in reserve where she doesn't have to cut every corner or max out profit at the expense of a better product on the pitch. She runs it like a business, but a FAMILY business and not a corporation.
IMO, we are lucky to have her. It's a shame that all PL clubs aren't run like this, and the rules aren't in place to make it happen. Every team should be run for the long term. Every team should have to make harsh decisions on whether to go for it now or wait. The owners should all just be able to break even so that they can easily recoup their initial investment upon selling but also not just spend at will or cheap out for profit. But without a salary cap, it won't happen.