Why was marie antoinette the 1st person to be executed during the ""reign of terror""?

Marie-Antoinette-Josèphe-Jeanne d'Autriche-Lorraine, or simply queen Marie-Antoinette, was a noble of Austrian origin. She was very unpopular and many French really hated her and hated the monarchical tyranny. She was a symbol of the ancient regime. Many people despised her extravagant lifestyle and she's related to the moral decline of the French monarchy. She also participated in political intrigues before the outbreak of the revolution.