Real talk the people of King's Landing are mostly trash from what the viewer has seen (even then that's generalizing of course) but there's almost no reason why Daenerys should have thought that or burnt the whole city down. They surrendered to her, they already feared her. At this point Kings Landing has no people to rule, so what's the point?
Also, her going mad was a very quick progression these past two episodes. Of course everyone predicted she would go mad but the way it was presented was so poorly. Most of her previous violent acts were justified (crucifying those dudes, killing royals to free slaves, etc), hell more justified than most of the lords and kings in the show. Yet she throws it all away because no one loves her? Lool fuck off with that shit.
She had her brother murdered via liquefied gold poured on his head while she watched.
She locked her friend and a Master inside a vault with no way to escape.
She burned alive all of the Dothraki leaders inside of a tent.
Shes done some pretty fucked up shit that isnt justified.
He was using her as a slave to get what he wanted
They betrayed her
Only after she witnessed the Dothraki raping women and trying to undermine her rule
So you are justifying her doing mad things over the course of 8 seasons and when she finally snaps because of all the L's shes taken the last 2 seasons it doesnt make sense to you?
Those weren't "mad" things. She killed people that were doing terrible things, 100% justified. She now killed a bunch of innocent people for no reason.
This is the same Daenerys that locked her dragons up after burning a child, the same one that killed men for rape, etc. It wasn't a steady descent over time into madness, like the other Targaryens, she just fell off in the last two episodes lol ---