mamba
Legend
I don’t know, there is an imagined part here, namely the value of the parts Hasbro kept, the other two are actual money however.The writeoff is the difference between the imagined money and the real money. That doesn't mean it was a bad investment. It could be bad, but it could also have been a good investment, just not quite as good as hoped.
Unless you think Hasbro is so bad at estimating the value of their properties that this can account for the $1.3B writeoff (i.e. the properties are at least that much more valuable than WotC’s supposed best estimate believes they are, or they had such unrealistic expectations before and are now more realistic about it), then this is an actual loss, at least for the most part. If I lose over $1B between buying and selling a company, I’d consider that a bad investment. That still gives you plenty of imaginary wiggle room for the parts they kept.
Just like you said, there is still an imaginary piece to this, I’d expect Hasbro to write off as little as they can afford to (ie following accounting standards), so there even might be another writeoff in the future. The imaginary part of this can still go in either direction…