You are going through latest and greatest syndrome right now. We all go through it when new products are released. I bet if I lived next to an Apple Store, I would spend $1,700 every year. Its just not practical thing to do though.
The 2017 is a fantastic laptop and you should try getting some more mileage out of it. You should not be looking to upgrade until 2020 or next year if you really need the performance.
My impulse buy nature had me wanting to splurge next year when I visit the US, but reading the discussions and watching the YouTube videos, it has brought things into perspective. The 2018, while a great upgrade is not a must have, especially for 2017 owners.
I am on a 2015 and I holding out until 2020. I usually don't visit the US until spring time, so I will be in a conundrum, because if Apple keeps up its current trend, I would be stuck buying the 2019 in 2020. That is unless I take another trip in the summer or fall.
So, give it some time and within a few months, you will have moved on from this period. I'm sure when iPhone season comes, the syndrome will appear again.