Unfortunately the muslim kings not only screwed up the country, they also converted a whole bunch of people by force and coercion to Islam
What is a whole bunch of people? 10,000? 50,000? 100,000? Please document your historical sources, otherwise you're just another liar, which is very typical of your kind.
I do agree that Muslim kings of India were arrogant, stupid and worthless. (But they did have Hindu generals and soldiers as well) Instead of wasting money, labor and time on a useless structure like the Taj Mahal, they could have built educational institutions.