Finland isn't a part of Scandinavia. The culture doesn't matter. A lot of countries share a "Western Culture". Doesn't mean that what happens in 1 country, happens in all of them.
This Wikipedia link actually describes it well. I am originally from Finland but been living abroad most of my life. After few years abroad I learned that there is no use to correct people "Finland is not Scandianvia" because apart from Finland and actual Scandinavia rest of the world says Scandinavia.
A lot of people confuse 'Scandinavian' with 'Nordic'. Scandinavia is a geographical description, Nordic is more cultural, which includes Scandinavia, Finland and Iceland.
I was actually considering including Estonia in my list, but they are not a member of the Nordic Council. And Estonia's Nordic bona fide is a matter of dispute. Personally, I believe Estonia to be a Nordic country, including having the Nordic Cross design variant of the Estonian flag hanging on my wall.
Furthermore, in an article about military history, Scandinavia is understood - in a military geopolitical context - to only include Denmark, Norway and Sweden.
https://en.wikipedia.org/wiki/Scandinavia#Use_of_Nordic_coun...