Squidward was in his 40s in 1999 meaning he had his prime years during the AIDS crisis. It’s likely he spent a large portion of his life closeted or self-loathing. It makes sense he would resent SpongeBob’s carefree lifestyle. SpongeBob is everything Squidward couldn't be
it's another kind of joy seeing characters you made moving around and interacting with eachother no matter how repetitive it gets lol especially if you're a an artist with low motivation