They don't need to justify anything. MK8 sold over 70m copies for 60 dollars each, has a 92 metacritic, and has consistently charted in the top 10 game sales and often much higher each week for the last almost decade. I refuse to check but it is probably the highest selling Nintendo game of all time if you don't count pack ins and maybe even if you do.
If there was ever a game that didn't need to justify a higher price tag vs other games, it's Mario Kart and Grand Theft Auto.
This is to show people who are Nintendo/Mario Kart fans what the game will be like.
Also, if you buy the bundle the game is only 50 dollars, lol. EVERYBODY who buys Switch 2 should also buy this game so there really is no excuse to play 80 dollars for it. Just buy the bundle and get it for 50 dollars, cheaper than even MK8 is today. Reread that last sentence carefully as it is very important and relevant here. There is no reason at all not to buy the bundle and get this game for 50 dollars. If you tell me "I'll buy the console today and MK later" NO, just save your money and buy the bundle. This is why rich people keep being rich. Be wise with your investment and get the game via bundle for a mere 50 dollars. Your arguments are as weak as well water.