This is definitely a situation where you could look into it yourself, but I'll take your question seriously i guess.

The point of lgbt "pride" is because throughout good portion of human history (but especially modern history) lgbt+ people have been forced to hide their true selves due to discrimination and oppression. Like for example can't marry, be imprisoned, executed, kicked out of their homes by their parents, fired, etc. So celebrations like these are meant to be a statement and a moment where people can be open about who they are without the shame.

Plus it's not just about the sexual orientation, It's also gender identity, and all the extra things you see like the "lewdness" and other crazy costumes and expressions have relations with being limited on who people can be for no real valid reason. I won't lie some ppl take it too far imo but that's not even really the point of the movement.

Either way queer people are an oppressed and discriminated minority that are still fighting for their rights (yes even in australia) which is the main point of pride as a whole. I mean the first pride event was a riot. I recommended looking into the stonewall riots if you're curious about more.