Why Use Proxies?

I was wondering, why do you need proxies? It's just a noob question, not trying to start up something controversial here. For example, I have GSA, and I was thinking of getting proxies, but heck, I'm not making money yet and they're quite expensive (for me). What's wrong with using no proxy? Does it prevent you from posting somewhere if your IP was banned? Or are there other reasons as well? Just trying to clear things up for myself thanks!

Your ISP (if you use your computer) or hosting provider (if you use VPS) will likely kick you off for spamming.

Also your IP will get banned pretty soon and you won't be able to do anything. A proxy IP address is just like a house address, with them you can trick sites in thinking that you are more people so that's why you need them basically.