Go with him if you want, but it makes you just as wrong as him. My portfolio has value, and this year's value is much greater than at any time in the past. By your logic, if I were getting a divorce my spouse would only be entitled to half of what I actually invested in my stocks and entitled to none of my gains. Fortunately, I didn't sell them, or she could claim more. I'd love to see the reaction I get from her lawyer when I make that case.
Imagine if my great, great grandfather had given me a Honus Wagner baseball card which is extremely valuable. I shouldn't care if the dog is drooling all over it because it's currently worth nothing because I didn't sell it. Go ahead dog, chew it up.
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