Yes. If you could prove transgenderism exists. See because you attach an -ism to it you are (in English) saying “the ideology of transgender individuals” which is “we exist” which is not an ideology. It is a fact. You can disagree with facts all you want but it doesn’t make you smart.or intellectual… it makes you wrong.
“The idea of being transgender” it’s not an idea anymore than you think about being cisgender. It’s a false dichotomy created by cisgender people who fail to understand the issue or fall victim to the “gay agenda” rhetoric of right wing media.
A better way to phrase it is no trans person thinks of themselves as trans. A trans woman thinks of herself as a woman. A trans man thinks of himself as a man. So there’s no “idea” of “being transgender” unless you’re a cis person who thinks they know what they’re talking about.
It’s like the phrase “differently abled” only able bodied people think like that.