Agree to disagree, I paid for a game that is about racing cars that have been know to be able to either be purchased or won through events in every past GT game. Not a gambling experience based on chance.
You need to shift your perspective, sir. With the Gran Turismo franchise, Kaz has focused on cars and car culture, through allowing you to experience and race various cars through-out the series, hence the tagline of "the real driving simulator".
For GT7, to really hone in on car culture, Kaz decided to make certain cars that are difficult to acquire in real life, difficult to acquire in-game.
Want that Shelby Daytona? Best get a job when you're 15 and start grinding away at life until you can afford one, maybe in your 40s. 'Best" way to translate that in to a game is give it a high price point and make races pay peanuts.
Want that Bugatti Veyron? Well that's a bit more affordable but still limited quantity, so chances of you owning one are still slim. Better, but slim. How to translate that in to the game? Either add it to the Legendary Dealership (I wish they'd done this and got rid of invite only cars) or make them Invite Only and make the invites rare.
End of the day, yes you purchased the game and all of the content. PD hasn't taken any of it away, it is right there in the game, they've just introduced game mechanics to make that content harder (but not impossible) to acquire, much like how those cars would be harder to acquire in real life. And they were upfront with this idea from the start.
It sucks, I still hope they do away with Invites, but chances are they're here to stay, so all we can do is grind away and hope.