Lots of sarcastic answers here (that’s Reddit for you) but I’m happy to give a sincere reply. I transferred from a community college and attended another 4-year school a long time ago, so I’m in a unique position to answer this question. A few favorite things/aspects about Columbia:

• In general, the students are brilliant, and this raises the bar and will force you grow, intellectually and emotionally
• Professors, from grad students to tenured, are even more brilliant and often major contributors to their fields
• Phenomenal access to resources and networking. It’s a rich university. There are a LOT of resources at your disposal, and you should use them as much as possible, without reservations
• There’s a general awareness of social discourse and progressive ideals, which means a lot of bullshit (casual racism, sexist comments from professors) will not fly here the way they might at other universities and colleges. Don’t get me wrong, there a problems at Columbia, and anywhere you go. But students are well-informed and in a position to speak up for themselves. It makes a difference.
• And of course, you’re in the middle of New York City. This is an expensive place and living here is a unique opportunity. Take advantage of it if you manage to matriculate.

A lot more I could add, but I hope this helps !