Easy boy, it's just like when Real wanted Zizou and they took him from us... or they took several other players from teams that weren't willing to budge...
PSG is no Real Madrid, but they got more money then them. and which ever club it might be, they can raid them. just think back to this summer, when Barca was persuading Thiago Silva. They told then to back off, or they might trigger Messi's release clause ( something like 250m). and guess what happened? Barca backed off, and Psg bought Barcas second choice Marquinos
They live in an intriguing city, have an impressive project going on and they have financial muscle. it's not like they are treating us like Livorno, but they really want Pogba. Because his a world class talent, and his from Paris, he could be the perfect poster boy for them. and Juve doesn't mind their courting of him and i'm sure that Juve has a price fixed at the back of their head, where, they accept the offer, if PSG are willing to offer that...