You seem to know a great deal, tell us more.
It's pretty obvious.
Tell me how they're supposed to afford Ronaldo's and Neymar's salary for the year and a big loan fee? How are they supposed to afford 150m euros on top of that? If you're going to say the same thing for Barcelona regarding Messi, Barcelona generate a lot more revenue than Juventus does.
If Barcelona and Real Madrid are in for you, you tend to not think about other clubs. Juventus would be a last resort for Neymar. He would literally only go there for the money, because Serie A is a pretty dry league. He would be in the same situation as he was when he went to PSG.... and he totally regrets what he did now.