Well well I see why people always complain about disc rot
Keeping discs in a car with major chances of temperature being very hot or very cold is a big no no, jewel case disc wallet or anything really, If you were to keep some of your older sega cd based games and even ps2 games in there for a longer time you can say goodbey to those games and hello to disc rot
Also not to mention people who buy games at fleamarkets, people want to get rid of their stuff so maybe it was stored in a cold or very hot place etc for quite some time. It's kinda expected that you will find some disc rot, people wanted to get rid of them games and treated them games like trash anyways.
If you were just to keep your discs in a normal enviroment disc rot should not be a problem at all.
Basements and garages aren't always the best places to store discs unless it has been made well wich usually they are not since it costs some nice money. Better than a car though way better.