I agree, there's a huge spread with, at one end, people who are 100% happy with their sex, and with the gender roles their society put on them. And at the other end, people so completely unhappy that they feel compelled to have medical treatment to fix something they feel is simply 100% wrong for them.
And in between there are loads of people who are happy with their sex but identify more with the other gender roles, and express that in various ways. Either by living as the opposite sex, or just by being a "tomboy" or a very feminine boy/man - and how we react to those people is very much about society and expectations. Currently, being a woman behaving in a more masculine way is fine, but for a boy to behave in a feminine way is seen as more of a problem.
In many cases, if we allow children to express who they are without pressuring them with too many gender expectations, then they can find ways to be happy with who they are, and hopefully many will not feel they have to have surgery. But there will always be a few for whom that is the only way they can square who they feel on the inside with what is visible on the outside.
When I was at primary school, the girls uniform was a skirt. I was determined to wear trousers, and boys shoes, and have my hair very short. Somehow my parents persuaded the school to let me, and for a few years I looked just like the boys. But, when anyone asked me "are you a boy or a girl", I had no doubt the answer was "girl", and was even surprised that they asked.
For a long time I felt like I was "dressing up" if I wore a skirt, and still wear trousers for most things, though I'm happy to wear a skirt now and then.
I'm glad my parents and school just let me do what I felt was right for me, and didn't either forbid it or send me to psychiatrists as if there was some major problem. I'm in no doubt that I'm a woman, and straight - but I don't think I'd put myself at one end of a binary scale when it comes to gender.