You know those days in the summer when it is opressively humid and so hot you don't even want to move? In Ohio, we get a couple every four or five years.
That's what it is like in Orlando around eight o'clock in the morning. It gets much, much worse by noon.
Add to it a gazillion people (all in iffy to bad moods thanks to the weather) crammed into one place, hurrying to get somewhere, stopping to look at maps, etc.
The weather is oppressive. The crowds are oppressive. You can't see your surroundings because there are too many bodies in the way. But that doesn't matter, because all you really care about is getting into a ride with air conditioning.
You say, "I'm so happy to be at WDW! I'm not going to let this heat or all the people ruin my fun! I'm going to have a positive attitude NO MATTER WHAT!" But at some point it wears you down. And the people you're with start getting on your nerves. You find yourself saying, "Okay, you're hot! I'm hot, too! See that woman? She's hot! We're ALL hot! Complaining about it helps nothing! I know you're hot, you don't have to tell me again!" This is brought up for years and you have to apologize for it so many times that you want to say something else that isn't nice.
You have to shower and change clothes during your mid-day break because you feel so skanky. Then you go back out and after 2 minutes are wondering why you bothered.
At some point, you will promise yourself that you'll never go back to WDW in the summer because you might as well have stayed home, you aren't having fun.
Oh, and it rains. Sometime between 3:00 p.m. and 7:00, the rain will start. It falls for hours. The folks who say, "It only rains for 20 minutes!" are totally full of it.
....
...then one day you'll decide it wasn't that bad. It is Disney, after all. A bad day at Disney is better than a good day at home. You go in the summer again. And it isn't as bad as you remembered...it's worse. Hot, hot, hot. Too many people. No fun.
Then you swear off summer for life.
That's my experience, anyway. Hope yours is better!