But what is that standard? If today someboday has a big house and two cars, and robots take his job in the future then can he expect his UBI will be enough to maintain the big house and 2 cars, because that is his current standard of living? I doubt that.

The standard shouldnt be "This guys personal idea of a living situation". Wed have to come to an agreement as a society as to what is part of that standard.

I think shelter, clothes, internet, and food would be a reasonable modern standard but that shelter doesn't have to mean a 3000 sq ft house, and internet doesn't mean they have the fastest connection speed possible in the area, and food doesn't mean steak and lobster every night.

That standard should increase as technology improves, for instance if we did this in the 90s having internet access would have been a luxury and not a requirement for being part of society, but it doesn't have to be something luxurious compared to the time period its paid out in