Look, I've been smoking weed almost every day for about 4 years and on and off for a lot longer...
I've done a lot of other drugs and grown out of them and weed has become my vice, and it's not terrible... I still function and things are fine.
But if you think it will make your life better, you're an idiot.
VICES ONLY MAKE YOUR LIFE WORSE.
Cig smokers get testy when they don't get nicotine; coffee drinkers can't function without coffee, and get hyper and annoying when they drink it.
Pot is a mild psychedelic. You won't notice it at first, but after you do a fuckload of other drugs, you can start to compare it to things like acid and see why it is that. It literally changes your mindset. And like it or not, it changes it for the worse.
Sure, you will become this deep thought machine capable of ideas which no one will ever comprehend, but your attention span will fade into nothingness and you will slowly lose all motivation to do anything other than get high and play video games. And trust me, there is SO much more to life that I've missed because of it.
So sure, it's fun and all to just do it once in a while, but just know... I starting smoking weed just "once in a while", I starting smoking cigarettes just "once in a while", and I started doing E, L, blow, and subutex (don't ask) just "once in a while".
And yeah, i know, weed's not physically addictive... at all.
But if you think a mental addiction is a joke, think about this, my girlfriend smokes, all of my friends smoke, and smoking weed goes hand in hand with 90% of my daily activities...
Not to mention, I enjoy smoking weed. I just would also like to stop.
tl;dr - NO drugs are necessary to have fun, and ALL drugs will make your life worse, but very few people learn that until it's too late. Be one of the smart ones.
EDIT: I have to say something about the gateway drug theory too. Pot is actually kind of a gateway drug. Just not in the way the government would like you to think. Hear me out.
Any sort of legal or illegal drug is a gateway drug. Almost everyone does them, sure. But I feel like "gateway drug" is a very loosely defined term. The "gate" is never obligated to actually show up, but it usually wouldn't be there if you didn't already drink or smoke weed. Er... Let me try and explain that better.
I smoked weed my first time with my sister, and I told my friend I was doing an experiment since we didn't know to much about it. Then, I started doing it a lot (partially because I joined a band). When I started smoking, I immediately got a shit load of new friends, and was accepted into this group, and it felt great. Then, salvia was just starting to get popular where I live, and it is still legal I believe, so back then I had no qualms about doing it. I mean, I already smoked weed.
But thinking back, I would NEVER have smoked salvia if I hadn't already smoked weed... Whatever though, some people would have, especially since its legal. So let's continue.
I slowly learned the possibilities of doing prescription pills and started to do them/ steal them from my family. Once again, this is another situation where I, personally, would never have done them without having already felt the joys of getting fucked up, but other people have.
Then we move on to ecstasy. My sister was selling E at one point (About 200 pills at a time.). And I was curious. By this time, I had smoked weed for about 2 years. I drank quite often. I had done some pills, robo-tripped, and had been addicted to nicotine and coffee for years. I still felt no different. My life was fine. Except that my girl had just dumped me. Regular methods of getting fucked up weren't doing the trick for that bit of sadness, and I felt like doing E once wasn't gonna kill me.
I don't really wanna keep going and describing my whole life for you, because it's a LONG story, but really, ANY DRUGS, LEGAL OR ILLEGAL, WILL MAKE YOU EVEN SLIGHTLY MORE LIKELY TO DO OTHER DRUGS, AND WILL MOST LIKELY MAKE YOUR LIFE SOMEWHAT WORSE IN THE LONG RUN. THE GAIN IN LIFE EXPERIENCE THAT YOU GET IS NOTHING NEAR THE LOSS OF COMMON SENSE THAT COMES WITH IT.