Huge amounts of money have been thrown around for the Seinfeld rights since the show went into syndication. Seinfeld and Larry David are both sitting at around a billion a piece and the main source of their wealth is Seinfeld. It’s been reported that Friends and the Office were bought from Netflix for around $450 and $500 million, respectively (estimated amounts that I don’t care to check for complete accuracy). I don’t think any official numbers are out on the new Seinfeld deal, but it’s probably easily over $500 million. When Hulu made a 6-year deal back in 2015, they agreed to pay out around $160 million per year, which would put the total cost at $960 million. If this seems like a lot, that’s because Hulu was setting a value of about a million dollars an episode.

And more on your second point, Seinfeld is pretty much critically regarded as a massive success and the comedy has translated extremely well even in the present day. The show was and always will be a massive hit and the proof is in the pudding, and the pudding tastes like cash.