What about when Sid's toys fix Buzz. Buzz was depressed and unresponsive until they repaired him. It seems like they'd be exactly the sort of toys who would think Buzz should be flipped off of demo. they start working on him before they have the arm, and You can even see Rockmobile pointing to the switch and giving a look like "do you see this? there's your problem".

Good thing he didn't have a evil setting as an option.

I always guess "Demo" means "reset the character mode"
and Play is like "free will" mode.
A limitation, to a freedom of character's mind.

I think “Demo” is..well, a demo. It’s what you get from the box. It’s so kid’s can try him out in the box before buying, without all of the features or voice lines being used. Only ones for the 1995 box demo. “Play” unlocks all of those, and let you have more voice lines. Out of box, you are supposed to change him to “Play” before first use. However, kids being kids, just want to play with the new toy, and not read any manual. Andy kept buzz in “Demo” mode. Where somehow, self conscious is only granted in “Play” mode, due to him not having to go strictly of those lines anymore. Going off of @RichardQue’s theory, I believe our buzz, when the toys in Sids rooms fixed him. Switched him to play. So now instead of being in a depressed state where his world doesn’t make sense anymore due to what he knows only from that code, “Play” unlocked everything, allowing him to have free will, and understand he is a toy.

Somebody's been holding my reset button too long.

Missed opportunity to put the next lines in Spanish.

I always wrote off Toy Story 4 Buzz as not knowing what a conscious was because of the reset Lotso did to him. Honestly I still believe that Lotso did break him in a way, if you pay attention to how Buzz acted before then and compare it to how he acts after that while he has the memories of the previous films he acts completely differently and almost like he's a totally different Buzz altogether. I'm not saying you're wrong in your analysis however I am saying I believe Buzz as he currently is in the franchise is somewhere in the middle still following his predesigned script as a space ranger but still aware that he's a Toy. it's not a binary 0 and 1 right now I believe he's at a 0.5 where he's using the logic of the "demo" mode with the knowledge and capability of the "Play" as you described it. Which is also why I think a lot of people didn't like how he was written in Toy Story 4.

(Disclaimer I have not seen Toy Story 5)

We don't know that this Buzz is the only one that has a sense of self. Presumably, all the others that left the toy store and went to a kid got their own sense of self, just with a different family.

My theory is that every Buzz Lighter the Toy Stores wanted to sell was put on Play mode meaning he only say his phrases when some one presses his buttons, but maybe the Demo mode was for the one who was probably in glass box or a diorama or something just that show it off and because of the demo mode that Buzz Lighters would say their Phrases randomly after maybe every 5-10 minutes just to attract kids to that aisle.

7:38 he was gonna say "delusional", but he was cut off. Not "deluded".

This makes me wonder what would happen if, by some miracle, Buzz saw a rerun of his toy commercial.

Buzz doesn't get amnesia in Toy Story 1. Therefore, he never switched modes in that film.

So, Andy could have switched it from demo to play when he first got Buzz.  The fact that he eventually becomes the Buzz we know now is much like the 800 series Terminators where their CPU's are set to "read only", but when set to "read/write", it becomes a learning computer.  The switch back to demo forces the original software to "reboot" Buzz and the reason it doesn't work like Woody thinks it does later is because Buzz has to remember everything again (albeit much quicker, of course, since he already knows everything).

Never thought I'd be randomly subjected to an existential crisis on Buzz Lightyear being an anomaly in the toy world possibly without a soul always being reset always different.

Like I believe that in the first movie, maybe the second, they captured all this without the toys knowing but by 5 movies… like it seems illogical. They must be in on it by now. How can they not know. With all the marketing, etc I think they are now in on it and it’s no longer real. Just my opinion.

I think bro's just high on something

Love and Loyalty is supposed to be WOODY’S thing. Which is what Andy and Bo even addressed. It’s just he’s insecure and causes him to act foolish.

Buzz’s thing is boosting self esteem and encouraging them to work together. He’s the one who ultimately brought Woody back to his senses in the first 2 movies. Buzz kept encouraging everyone during the second movie, and His theme in the 3rd movie was “stick together and we are friends”.

Though I think the 4th movie should be taken with a grain of salt as it didn’t understand any of the characters and their motives,

I like to think Demo mode is how the corpos who own the toy line and franchise want you to see the character and Play mode is what the kid imagines and sees in the character. The moment they leave the shelves, they are no longer owned by the store, but by the kid who tells their story with them :')

Play probably defaults to Delusional Buzz too, and that’s why the switch doesn’t work.  Demo setting are used for displays in stores, and usually shut off by like a pull tab, the sort that sometimes block batteries, rather than a literal switch.  Ordinarily, I would expect that Play mode should be set BEFORE being put in the box to be sold, at the factory.  The option to rest by flipping to demo is a way to reset a toy that’s buggy, for the consumer to rest themselves rather than throwing it out cause voice lines aren’t playing right or something.  

But they ARE sapient enough to learn and realize.  It just takes time and an existential crisis for our Buzz to get there.  A factory reset probably just doesn’t last very long on a Buzz with memories.

6:44 "I am the Eggman"

Never noticed the company name on that truck before.

Living toys is weird enough.