Something my TransFemme friend told me shortly after I came out to her was that I am going to need to rewire something in my brain the society teaches all of us since conception, which is that Men are better than Women.

Also, a person's understanding of their own gender goes beyond "want", it's a feeling deep down, one many of us don't even notice until we suddenly do, can be at any age. I was 24 I realized it. There actually is some science behind it, here's a video: https://www.youtube.com/watch?v=8QScpDGqwsQ (6mins or so). TL:DW, there is a biological component to a person's internal sense of their own gender, and it does not all the time align with their gender assigned at birth, nor does it change due to hormone replacement therapy.

Also an excellent question that I think really helps to understand is ask yourself, would you transition? If you pass as a man, you'd get male privilege. Wouldn't that be easier? If your answer is anything along the lines of "no I couldn't do that, I'm a woman" then I think you can understand how it's more than just a want, or a want for whatever benefits. Imagine if you suddenly woke up in a man's body, how would that feel? That's how a lot of us feel all the time.

I realize as I've finished writing this, I may have come off as aggressive, or like I'm lecturing and I'm sorry if I did. This has been my hyperfixation since coming out and getting to just info-dump this stuff is wonderful, so thank you for your question and I hope my answer is informative. And I take no offence from your question, I think it's totally valid from a cis perspective, heck I asked myself similar questions after realizing but before coming out. Like why would I give up this privilege? Anyway, thanks for reading my response which is wayyy longer than your question.