I feel like there's two distinct questions wrapped into one, in this thread.
The first one is - is Sancho worth a top end transfer sum ("100m+")?
And there, the answer is uneqivocally, absolutely, yes.
In the context of player prices over the last years (Mbappé, Griezmann, Joao Felix, Hazard on his last contract year, Coutinho, Pogba, all commanding three digit million sums, players like Havertz, Pepe, De Jong, De Ligt between 80-100m €), and considering the kind of talent he is and the kind of record he has at a young age, he is objectively 'worth' that kind of transfer fee.
(putting aside the simple fact that a player's price is what the club he's under contract at is willing to sell him for)
Covid put a dent into clubs' earnings and made their planning more insecure (which is probably the main reason why the transfer didn't happen last summer), but going forward the money will still be there. And whoever buys him will get a 21 year old top player with a long, quite likely elite career ahead of him, and a record to show for that can compare with the absolute very best at that age. Of course his price will be that high, he is that good.
The second question is whether a club should afford him if that means compromising other positions, that may or may not be in more urgent need of reinforcements?
That's of course a debate worth having, and for Man United I for one wouldn't be able to give an answer. From the outside, I tend to think though that Man United can afford a lot if they want to. 'Other clubs can only dream of' that etc, so I'm not sure why there would need to be either/or scenarios.
Now, what's not an acceptable operation, is to conflate the two arguments in order to create some kind of reality where the answer of the one conveniently changes the answer of the other. You can't say "we don't really need Sancho that badly so I think he's worth 50m at best".. He will be worth his value to someone else.