You can.. You just have to be good and ADVERTISE YOURSELF!! Comment on other singers' videos..Get out there! No one's going to find you if you don't do things. :)
Can you be famous like justin bieber if you sing in youtube?
If you can sing good and someone might be looking at you who might pick you up. So yes you can.
Only if you are able to sing, have that swagger in your videos than for sure you will be famous.
If your good and choose pop,rock,metal,or rap then yeah!