Optimism that one day it'll be okay and the change of going will work out.
Plus lots of people's holidays this summer are postponed ones from last year.
We have a holiday abroad booked for the end of October. Its been booked for a long time so we were expecting to be able to fly there by that time, when we booked. It's amber so technically could go according to English rules, but only if the US change their rules and allow us in!
However the flights were relatively cheap (for the dates and location) and they are refundable up to 3 weeks ahead. We can also make date/route change up to 2 hours ahead, all without financial penalty. The hotels are full refundable until 24 hours ahead. We will make the decision nearer the time and see what's happening once we unlock next week.
I don't begrudge anyone booking it going on holiday abroad this summer. We've all had a long difficult year and a half - think so many people are ready for a break and a return to some form of normality; for many normality in the summer is a family holiday in the sun.
I asked my class yesterday about their mobs and at least half had trips abroad booked - some holidays, some families. All in Europe. I hope they get there and have a wonderful time.
My own teen Dd has been away - she went to Portugal to visit her best friend for a few days. She had an amazing time. I was a bit stressed as the rules changed before she went but luckily her dates weren't affected. I'm glad she was able to go.