But if my battery has lost 10% then all the joy will be gone out of using it. I'll just be thinking about how to pay for the battery replacement every time i get in the car.
Unless the battery was too small to begin with, you won't even think about it. I normally only charge mine to 70% anyway, so the difference between 100% of capacity or 90% is completely irrelevant on a daily basis. For long road trips it's also irrelevant, since it's most time-efficient to charge to only 70-80% -- charging slows way down as you get close to full.
So, why not get a smaller battery if you rarely use the whole thing? Two reasons: First, so that losing a little capacity or charging to 70-80% is still sufficient range. My first Tesla, a 2014 Model S, only had 200 miles of range when charged to full, and that meant that time-efficient road-trip charging required stopping every 100 miles, which is too often. Second, because using the full range of the battery causes it to lose capacity faster. So, you buy an EV with a battery that's 30% larger than "needed" in some sense. Losing some of that doesn't matter.
So, you wouldn't think about how to pay for a replacement every time you get in the car, because you wouldn't plan to get a replacement, ever.