It makes a disgustingly big difference.
Assuming you have €100, and spin at €1, you will be able to do on AVERAGE 4951 spins at 98% RTP before the balance reaches 0.
On 96% RTP this average totals to 2476 spins.
You clearly have no idea how RTP works, no offense, but the 'billions of spins' only applies to accurately calculating the average, it does NOT mean that you will only see a difference after a billion spins. Attached is a chart for your convenience.
Again, on average starting with 100x stake balance:
98% RTP = 4951 spins
96% RTP = 2476 spins
You don't need a billion spins to feel that difference bro. Pay attention to RTP.