Of course GT7 will be around for several years and yes, there is no rush... but...
The price of the most expensive cars in the game, coupled with the low rate of income of Cr. earned from gameplay, the absurd cost of credits via 'microtransactions' and the frankly cynical limit on free credits one can acquire (20 million) makes it nigh on impossible to collect some of these cars without paying an obscene amount of real money for them.
Based on ca. 2 hours of daily gameplay, I can expect to earn ca. 1 million Cr. a week, and half of that is likely to go on regular cars, parts and customisation (otherwise known as 'playing Gran Turismo'...). But even committing 50% of my earning to save up for high end cars will mean a maximum of around 26 million Cr. a year, but crucially we are not allowed to hold this much earned Cr..
In order to buy some of the big ticket cars, one would have to stop spending earned Cr. completely, and play the game for 2 hours a day for 280 days in order to buy just one 20 million Cr. car. That, or top up one's Cr. with real money purchases from the PS Store. But at £16/$21 for just 2 million Cr., that is not a fair option IMO. Of course, this would come at the expense of purchasing any other cars in the game, stopping all upgrades and customisation, and effectively killing much of the game.
So, no. It is not about patience, it's about the in-game economy fundamentally changing the way the game will be experienced by millions of users.