[ted]

If you have gone fast on track and on the street you know on street you can't get near your limits on the track.
At the track, you have safer run offs, fire crew, ambulance, surrounded by other track drivers.
On the street, run offs are cliffs with trees, families in cars with cell phones, a helo for an ambulance just a massive amount of liability and exposure.

Don't assume because you are smart and successful enough to be able to afford a GT3RS lease payment that you also have the judgement, maturity and car control experience to actually drive it fast.