The reason for op was getting to his vacation place faster, so I guess we were discussing 1 reason.

The difference between not traveling and a 15 hour flight is huge (especially if you have a family those 15 hours away). But the difference between 15 hour flight and 8 hour flight is marginal in that context. And this is compounded by the fact that there are some regions which are geographically closer then Australia, but take significantly longer to travel to because they lack the infrastructure for fast and convenient travel. So honestly 15 hours is not that bad.

Yes, strictly you don’t need to travel anywhere, but we should allow people to travel in the most economical way feasible. Supersonic jet travel is not that.

If 15 hours in an economy class is too much for you, but you can afford a supersonic flight ticket, perhaps you should consider upgrading to a business class. Or if you don’t like that, consider braking the flight up in 2 or 3 parts sleeping at a nice hotel in between. This is a much more climate friendly option then a supersonic flight that only saves a few hours of your time.

If you have everything you need in your living area then you don't need to go anywhere else, yeah. In most places you can get everything you need within a 200km radius of where you live, unless you have very particular needs.

I'm glad you considered all possible ways to mitigate the environmental costs of flying. Seems like wasteful supersonic jets aren't one of them?

Would be cool, sure.