You omit the fact that 2/4 of the countries in the Uk voted to stay. You act as if the Uk is one country. It's not.
You ignore the fact that while concerns over boarder control and immigration may be valid, and while the EU may not be democratic leaving the EU has taken away the freedoms of many of the people living in the UK.
There's a petition with over 2 million people who want to have a debate on the topic of reversing the Brexit. Turns out people voted thinking it wouldn't matter.