Except Disney and Marvel are the ones who have managed to get this character back to the spot he is currently in. Sony failed with rebooting the character not once but TWICE on their own. If they're the ones who were doing most if it then I wouldn't be surprised if they wanted more money for it.
Again, how do you look at just the past few months with Avengers: Endgame and then Spider-Man: Far From Home and all that success and think "Nah, but we don't need Marvel". That's why Sony is dumb.
Just because they didn't want to lose their grip on it further doesn't mean they don't recognise the role marvel played. They can recognise that Spiderman would be much bigger with Marvel support while also not wanting to agree to hand over more.
It sucks for consumers but it's business, and neither party takes the full blame. Disney wanted more, Sony didn't want to give them more.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)