check the wiki, its better than the 'answers' given in this forum.
vampires are very very rare, but to be a vampire not only would you have to find a vampire, it would have to be a powerful old one capable of stealing your soul and turning you into a vampire. regardless of what the post above says of you losing control of your character, thats not true....you just lose your soul, and now if you die even once youre permadead because there wont be any 'spirit walks' to get back to your body...
if in the very very rare chance you do turn into a vampire, you would have to survive the intitial period where you are a weak vampire only being able to suck part of someones soul, meaning you need more meals, meaning every time you try to feed you risk yourself getting killed. after surviving for years you turn more powerul, eventually you will be able to steal souls and live way longer without feeding. if a vampire is killed, all the souls you hold onto are released to the akashik records for other players to be able to use them again. so vampire playstyle is extremely difficult as they are kill on sight and players will coordinate themselves to hunt you, assuming they have found you to be a vampire.(vampires are hard to detect).
the more souls you steal , the stronger you become.this isnt in the wiki, but i suspect you might be able to steal talents along with souls aswell.
there are also dhampyres. they live normal lifespans but dont appear to age. and they are extremely good at hunting vampires. they are vampire/humann hybrids.
caspian also recently stated that the first vampire we come accross may not be mann.
now, if you were to personally try to explore and become a vampire chances are you wont succeed. BUT a lot of people will think like you, wanting to be vampires.... you can use that thirst they have and form groups with them, build a guild/association maybe an assassin guild with a secret purpose of finding out everything you can about the subject. Who knows, this game is so unique there might eventually be an entire group of people coordinating together as vampires, with their vampire king like in skyrim. its possible... some may say not probable.... but knowing us gamers and our ability to coordinate coupled with our infatuation with vampires, i wouldnt be suprised if if vampire guild actually happened in game....but it would definitely take some time. probably a few lifetimes even after contacting the first vamp.