LEAVE HIGH SEC, I don't care if you move to low sec or null sec, but leave high sec if you ever want to experience Eve in it's purest form. If you are enjoying Eve and have only lived in high sec, you're going to love it when you leave high sec. High sec certainly is a necessary aspect of Eve and it serves its purpose to allow people to learn the mechanics of the game in the comfort of their crib, but if all you ever know of low sec and null sec is "Pirates are waiting there to kill you" then you are missing so so much of the game. I do recommend you stay in high sec long enough to learn how to fly, trade, explore, at the basic levels but eventually you have to cut the umbilical cord if you want to REALLY enjoy Eve.
There are so many features that exist in the game that you will never experience in High sec because the game mechanics don't allow it. My first battle next to a carrier was awesome, and I can't wait to meet my first Titan. Aside from Orcas, Freighters and Jump Freighters, you will never witness any capital and super capital ships in high sec, meaning you will never see the awe inspiring carnage or purpose each was designed to perform.
I remember roaming null sec for the very first time because I had to find out what all the hype was about, only to be jumping from system to system and slamming into a warp bubble. I was thoroughly confused and scared that I was in warp and all of a sudden I was yanked out of warp and stuck in a warp bubble like a fly in spider web. Luckily my first bubble experience didn't have anyone camping the bubble like they were supposed to, so I lived through that experience, unlike my second and third encounter with them.
Stealth Bombers are ships that you fly in high sec, but you will never know the sheer destructive power of a stealth bomber fleet until you go to null sec. Bombs aren't allowed in high sec and low sec and can't be launched there, but the gloves are off in null sec. A small fleet of stealth bombers will decimate a battleship in seconds if properly trained, a large fleet can be terrifying because you never know when they'll uncloak, target paint you, and let the bombs fly.
Sovereignty and owning your own system comes with so many perks and potential to become filthy rich it's ridiculous, but it also comes with a lot of responsibility and risk. Being able to control how many and what kind of cosmic anomalies spawn in your system and having them instantly respawn when they are cleared out is awesome! Having a hostile takeover of your system and losing sovereignty while all your expensive shit is still docked at the station now owned by the enemy corp is terrifying.
Jump drives and Jump Bridges are another essential aspect of living in non high sec space if you want to transport large amounts of cargo, or move fleets from region to region with ease. I have yet to experience either a cyno jump or a jump bridge, but I'm looking forward to it.
Aggression and is also more wild and untamed in null sec and low sec. You can also destroy someone without CONCORD intervention for whatever reason you want. If someone pisses you off, looks at you funny, enters your home system, happens to be flying a ship you don't like, decided it was just going to be fun, or just because you can are all valid reasons to shoot someone. In high sec someone has to have their corporation declare war on your corporation to be able to legitimately shoot you in high sec, you have to commit a criminal act, or accept a duel.
Player Owned Structures, POS, unleash their true potential with moon mining, super capital ship construction, and even though they provide a lot of defense, they can just as easily be crushed by the right fleet. POS Bashing can be very profitable depending on the loot that gets dropped when it's destroyed, but it takes a lot of firepower to bring one down, don't attempt this unprepared.
There are people that prefer high sec, and that's fine. Eve needs people to live in all areas for the ecosystem to work and function properly. You may find out that you hate null sec, or hate low sec, or hate high sec, all that I ask is that you experience more than just one area of Eve or you are truly missing out. Much more death and loss of ships occur in low sec and null sec, but it's well worth it.