The thing is, his desperation is entirely of his own making. He was offered enough money and support to get by with no problems in the first episode, but turned it down because he was too proud. He put his family through everything in the show entirely because of his pride, all while saying he was doing it for them. I’d argue he was a bad person from day one.
Definitely not, I played GoW 2018 first. I loved it so much that I went back and played every other previous GoW before GoW Ragnarok came out. The others are very different (but still very fun) games, and it definitely makes you appreciate Kratos’ story better, but they are by no means essential.