Why move the entry point to a separate class?

Question

Java

While learning java, I often watch YouTube videos of other people coding and solving different problems. I noticed that some of them leave the entry point in the main class, and some take it to the launcher class. In this regard, the first question:
1. Why take out the entry point in a separate class?
Of those who do this, some initialize the program in the main function, and some create a thread in which the launcher class constructor is called. Of course, I still understand the threads, but
2. Why create a new thread if the program has its own?
I tried both and, to be honest, I do not understand what the difference is.

import javax.swing.*;

public class Launcher {

  public Launcher() {
    JFrame main = new JFrame("Java calculator");
    main.setSize(360, 448);
    main.add(new UserInterface(main));
    main.setLocationRelativeTo(null);
    main.setResizable(false);
    main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    main.setUndecorated(true);
    main.setVisible(true);
  }

  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        new Launcher();
      }
    });
  }
}

Answer 1

In short, it starts the launcher in an EDT (Event Thread Dispatch), since Swing is thread-unsafe and all GUI operations must be started on new threads to avoid freezing and other program behavior problems.

Answer 2

Why don't you ask in the comments under that vid?
The situation "there is some uncle doing like this - why is he doing this?"