Yes, that's theoretically possible. Of course, we have no idea what the actual financial dynamic was inside that home - Tiger has a reputation as a cheapskate, so we really have no clue what kind of "allowance" she was on, but I'm sure she probably didn't have want for anything.
There was a prenup, so even in his death, she may not have inherited all of it or even $100M. We'll never no for sure, unless one of them talks about it.
Lastly, the receipt of matrimonial assets in a divorce are not taxable. This is a common misconception. Whatever Elin received in the split, is hers to keep in it's entirety.
“Whatever Elin received in the split, is hers to keep in it’s entirety.”
Here in Texas (a community property state), everything he earned from the date of the marriage was hers to begin with, so she’s just keeping what’s hers.
Colonel, USAFR