What's the goal in Minecraft Survival?

First time I played that game was like I'm so addicted but after downloading some mods, I feel like I'm so bad like a spoiled bratt and I thought what's the point of continue playing? Now I hardly play minecraft. The question is what is the of point building, digging etc when in you can actually expect it to happen in the end without any challenges at all?
Plus the gameplay of Survival makes non-sense at some point. Peacefull mode? And the Hardcore mode? What the hell?! Can we just make it to straight survival mode without any deactivating monster spawn?
Lastly, does this game has a boss or something or story? Can anyone tell me why I should keep playing Survival? I also removed all of mods now and please don't link me to any mods okay?

Technically the "boss" is the ender dragon. You can kill the dragon and take its egg. Once you have killed the dragon you have pretty much beat the game and credits will roll, but you can keep playing and it is possible to respawn the ender dragon in the end so you can do it all over again.

I play Minecraft with my kids on survival and for us the fun is just adventuring and trying to survive while looking for cool stuff. I usually try to fill out my map and look for villages and other resources to build a sweet house and garden. For us survival and adventure are the fun.

With mods you can set up different challenges for yourself. Just watch some youtubers who play with mods for some ideas "Popular MMOs" or DanTDM "The diamond minecart" come to mind when I think of playing with mods.

Now as far as the different Survival modes in minecraft go think of it this way. If survival is not challenging enough for you you can up it to hardcore to give yourself more of a challenge. As for putting survival into peaceful mode that can be useful too, especially for a world that you built in creative. I have a creative world that I built all kinds of cool stuff in: a shooting range, a house with lava on the floor, a gladiator ring, a halo type arena and a giant obsidian test area to blow stuff up. Now if I want to go battle one of the kids in the arena or go try to make it thru the "floor is lava" level I will go on Survival Peaceful mode so that I'm not bothered by monsters while playing my level and we can still kill each other on the game unlike in creative mode.

The cool thing about minecraft is that if you are creative enough the possibilities are almost endless.

Its just the feel of the game. You can be as creative as you want basically. And the survival mode just adds to the Realistic feel of the game. I know its not realistic but in a way it is. And the reward of collecting itmes in survival just thrives people for more. That feeling whe you find diamonds after hours of mining, or after building a massive house that took you all day, it feels amazing.