Many people travelled, emigrated, and worked and studied abroad regularly before we were in the EU.
Do none of the Remainers have older relatives, friends, aquaintances or colleages who travelled in Europe and around the world when the EU didn't exist?
Just one example: Inter-Railing was introduced in 1972, which is 20 years before we joined the EU. There were various currencies to be found as the Euro didn't exist, there were borders between countries, and yet somehow countless young people enjoyed Inter-Railing around Europe. No EU required.
[[https://en.wikipedia.org/wiki/Interrail]]
"1972: The program launched as "Interrail 72", limited to travellers 21 or younger. It covered 21 countries: Austria, Belgium, Denmark, East Germany, Finland, France, West Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland, United Kingdom, and Yugoslavia. The initial price in the United Kingdom was £27.50 for one month's travel."