Consider just saying you are not open to discuss the idea, or that you hold it self-evidently true that things are better now.

The way you phrase it you are preemptively insulting people who hold different views (or more likely different ideas of 'worse'). To be clear, suggesting someone "isn't thinking" or doesn't have a brain, is still an insult. This can lower the whole tone of the conversation.

In real life, I have to do something similar to certain people on religious topics, people who I can't call mindless idiots to their faces without immediate repercussions. I find its a great way of letting people know politely, that I will not discus the topic.