Selfie sticks are definitely a handy piece of equipment — they allow you to capture a much wider angle than you ever could otherwise with your smartphone alone, and they also give you the option of operating it more safely in the water and other potentially damaging conditions.
Obviously, professional YouTubers don’t utilize the cheap selfie sticks that you can find going for a dozen bucks. There are higher-grade aluminum models that suit studio conditions better, such as the Accmor AC-13TR.