Only make stuff you like. For example, I have a world of warcraft gaming channel that gets a metric ton of views but I don't enjoy the game currently. My nature videos are not going to be anywhere near as popular as my gaming stuff but it doesn't matter. No matter what you're into, if you keep at it, allow yourself time to improve at your craft, you will get better. Almost any channel, no matter how popular, you can go back to their earliest videos and see just how far they have come in quality and in perfecting their craft. This goes for anything, not just youtubers.