Fear. That was her gain. Her conversation with Jon set her down the path. She knew she would never have their love or loyalty so she would take and hold the Throne by fear.
The more I think about it, the more it makes sense to me. She probably played this moment a thousand times in her head, but it was never like this. She truly believed she would be met with cheers from the people. That the Kingdoms had been waiting for her, their ‘rightful’ ruler. Nothing turned out like that. She wasn’t welcome. She wasn’t the rightful ruler. She lost Jorah. She lost Missandei. She saw people running from her, not too her. She unraveled and then she snapped. She said people could die in their old world or live in her new one. She choose to make good on that.