Why do people think my sexuality is a mental disorder and/or invalid?

Well there's no particular answer for this, I believe that the reason people think this is because they have a lot of hate they need to get out, and so they're making excuses as to why they're not extremely loving and accepting. A lot of people just don't want to accept the fact that our society is becoming more and more accepting of LGBTQ+ members, sadly, so they try to convince themselves reasons to be hateful.

Sadly, many people still see it like this because that was what they thought in the past. We know it isn't true, but it's often hard to change someone's mind. If you care about them and they care about you, you can help them to understand and accept it.

People think your sexuality is a mental disorder and/or invalid because they don't understand. It doesn't mean that it is.

People fear what they dont understand. But it does not make anyones sexuality invalid, or worthless.

Because, and this is a true fact, being Gay, Lesbian, Bi, etc., used to be labeled as a mental disorder, thank god it's not anymore but some people are still caught up in the past!

A lot of people are still very closed minded and set in your ways. The person / people you would like to understand most, sometimes understands the least. It's important to surround yourself with people that really make an effort to understand and accept you for all you are

Because they haven't been through what you've been through. Everyone thinks differently and even tho they are wrong, there isn't much to do. You can't change the way they were raised, the way they were thought what's right and what's not. It's your life, so don't be dejected by others, you can live however you want to live, however you feel more comfortable.

People, sometimes, tend to disagree with what they don't understand. They have not walked a day in your shoes, and as a result, they cannot empathize with you. Since they cannot empathize, they cannot validate your feelings/situation. I want to assure you that your sexuality is not a mental disorder and it is valid :)

Its because they were raised with internalized homophobia/transphobia/ etc. and in most cases do not understand how severe mental disorders can be. My advice is to leave those people or disregard their thoughts because they obviously are wrong- if they are a friend who is homophobic towards you, then they aren't your friend. People who invalidate others make me angry, and rightfully so, but you just have to remember that they were probably raised in environments that invalidate sexuality and mental disorders, and that it isn't entirely their fault (even though part of it definitely is their fault).

From our very childhood, our perceptions about the world are shaped by the behavior of those around us. In a world where heterosexuality is a norm, it is not surprising that other sexuality can be frowned upon. In fact, I believe that identifying oneself as having an alternate sexuality is a moment of revelation that actually opens his or her eyes to the true vibrancy of the sexual spectrum. Till that moment of realization, the truth maybe that you yourself would wonder what is actually wrong with 'the others' . While it is true that other people have no right to decide what is right or wrong for us, it is also not really right to blame them completely for their wrong impressions. But please don't take this as an excuse for their intolerance - they are intelligent, mature people - they can very well adapt and look beyond such prejudices and consider us no less than them if they wish. My point here is the reason people think as you say is mainly due to social programing and a lack of understanding and empathy. Don't let that hold you back. Those who truly care for you will stand by you no matter what. Rest can mind their own business.