@PedroMendez great questions, and I honestly would have wanted to ask you similar questions.
I have no idea about what's going on with the latest lawsuit, or whether Neymar really have paid back his fines. But his move to Qatar is definitely a move from all the legal troubles that was about to be caught up with him, I believe. He will be protected at PSG by the Qatar bosses, as long as he manages to be their poster boy, which I believe he will manage gracefully. I would guess it is tough for the authorities in Spain and Brazil to catch him (- and specifically more difficult to catch his father), when he is surronded by the arms of Qatarian power.
And after all, Paris is a big mesmerising beautiful city, as he is going to a club with a big project, with the aim of establishing themselves as one of the big dogs in the Champions League - and he is suppose to be the last pussle that enables it.
I think these reasons in consideration - the qatarian power and protection, being the poster boy of a big project - makes the move lucrative for him and his father. Obviously, the Ligue 1 is not one of the top 3 leagues in Europe, and that is probably the only downside for his transfer, but he can probably live with it.
And I guess Neymar Jr and Neymar Sr won't (or can't?) pull off the similar 'stunts' in future contract renewals, as they did with Barcelona. I am guessing that their new boss has too much power to be mess with.
But to be fair, Barcelona (Rosell&Bartomeu&co) brought this on themselves. The desperate need of getting Neymar - i.e. a 'Crack' - made them do some dirty side deals, and those controversial deals gave Neymar and his entourage too much power over the blaugranas, hence why he could get away with giving them a headache by each contract negotiation, as well as with this summer's transfer story. I believe - despite Neymar being one of the world's most wonderful football players - that this is a deal where all three parties are gaining. With Neymar's wages and insane sign on bonuses off from Barcelona, Barca will have room to breath and bring in 1-2 anticipated reinforcments to the midfield. Question is whether it is not too late to find a crack signing for this summer, I doubt there are any clubs left willing to negotiate about their star, now when the season is about to start.
And considering what the rich premier league clubs have done to the market (the transfer prices on Walker, Morata, Lukaku, Mendy, etc. ) any club could easily put the price tag of 120 - 150 million euros on their player, especially when they know Barca have just received 200 million euros.